> ## Content Index
> Fetch the complete content index at: https://macfixly.com/llms.txt
> Use this file to discover other available public pages before exploring further.

# How to Sign a PDF in Preview: Step-by-Step Guide for Mac Users
- URL: https://macfixly.com/sign-pdf-preview-mac/
- Published: 2026-10-06T21:13:00.000Z
- Updated: 2026-10-06T21:13:00.000Z
- Description: This guide shows how to sign a PDF in Preview on Mac using handwritten or digital signatures with easy step-by-step instructions.
- Author: Macuser
- Tags: PDF Editing, Mac Tips, Digital Signatures, Productivity

Imagine receiving a PDF contract that needs your signature before the end of the day. You want to complete this quickly on your Mac without printing or scanning. Learning how to sign a PDF in Preview can save you time and hassle by allowing you to add your signature directly within the app.

This article guides you through creating a handwritten signature using Preview’s Markup toolbar and also explains how to apply a digital signature for added security. You’ll also find clear distinctions between electronic and digital signing methods to help you choose the best option for your document. Finally, troubleshooting tips will help you resolve common issues that may arise while signing PDFs on your Mac.

## Key takeaways

- Use Preview’s Markup toolbar to create and save a handwritten signature with your trackpad or camera.
- You can digitally sign [PDFs in Preview](https://macfixly.com/p/05a42e6c-0982-45ca-ae25-19d6f7ae7dbc/) using a certificate for enhanced security and authenticity.
- Saved signatures can be easily reused on multiple PDFs without recreating them each time.
- Sending PDFs for signature through Preview requires exporting and sharing the signed file via Mail or Messages.
- Troubleshoot by checking Preview permissions, ensuring the PDF is not locked, and verifying signature tool availability.

## Before you start: What you need to sign a PDF in Preview

To sign a PDF in Preview on your Mac, you first need to ensure you have the right tools and files ready. Preview is the default PDF viewer and editor included with macOS, supporting handwritten signatures and basic digital signing features. It works on macOS versions from Sierra (10.12) onward, so make sure your Mac is running a compatible system. The PDF file you want to sign should ideally be under 100 MB for smooth handling, though Preview can open larger files if your Mac has sufficient memory.

You can create a handwritten signature using your trackpad, built-in camera, or an iPhone connected to the same iCloud account. This flexibility helps you capture your signature easily if you prefer a personal touch. Alternatively, Preview supports adding digital certificate signatures, which provide enhanced security by verifying your identity through a digital certificate. Understanding the difference between these two methods will help you choose the one that best fits your document requirements.

Before you begin, it also helps to have a basic familiarity with where your files are stored on your Mac—whether in the Downloads folder, Desktop, or a specific Documents subfolder. This makes locating your PDF quick and straightforward when you open it in Preview. Having these prerequisites in place ensures a smooth signing process without interruption.

1. Check your Mac’s operating system by clicking the Apple menu and selecting **About This Mac**. You should see macOS Sierra (10.12) or later listed. This confirms Preview’s signature features will work properly.
2. Locate the PDF file you want to sign in Finder. When selected, you should see the file name, type "PDF document," and a reasonable file size (usually under 100 MB) displayed in the preview pane or info window.
3. Make sure you have a trackpad, camera, or iPhone ready if you plan to create a handwritten signature. You should be able to activate these devices when prompted within Preview’s signature creation tool.
4. Decide whether you need a handwritten signature or a digital certificate signature. Preview will prompt you accordingly when you start signing, so understanding this ahead of time saves confusion.

## Turn on PDF preview and open your document in Preview

To start signing your PDF, you first need to ensure it opens in Preview, the built-in Mac app designed for viewing and editing PDFs. Setting Preview as your default PDF viewer streamlines this process, so PDF files open automatically in Preview without extra steps.

1. Locate any PDF file in Finder and right-click (or Control-click) it. You should see a context menu appear.
2. Choose **Get Info** from the menu. A window with file details will open.
3. In the **Get Info** window, find the section called **Open with:**. Click the dropdown menu and select **Preview.app**.
4. Click the **Change All...** button below the dropdown. A prompt will ask if you want to make Preview the default for all PDFs. Confirm by clicking **Continue**.

When this is done, double-clicking any PDF will open it in Preview by default.

To open a PDF directly in Preview, you can also right-click the file, select **Open With**, and then choose **Preview**. The document will open in a window showing all pages in a sidebar, ready for you to view and navigate.

Use the sidebar on the left to scroll through page thumbnails or click the arrows at the top of the window to move between pages. This helps you confirm you have the right document and can find where to add your signature.

If Preview does not display the PDF correctly—such as missing pages, distorted images, or the file fails to open—try these steps: first, ensure the PDF file is not corrupted by opening it in another reader like Adobe Acrobat Reader. If it works there, restart your Mac and try opening the PDF again in Preview. Sometimes, outdated macOS versions or Preview bugs cause issues; updating your system can resolve these problems.

Additionally, some PDFs with advanced security settings or digital rights restrictions may not open fully in Preview. In those cases, check the document’s permissions or request an unrestricted copy.

## Create your handwritten signature in Preview

To add a personal touch to your PDF, you can create a handwritten signature directly within Preview. This saves your signature for repeated use, making signing documents quicker in the future.

![Create your handwritten signature in Preview – how to sign a PDF in Preview](https://macfixly.com/content/images/2026/10/sign-pdf-preview-mac-2.webp)

1. Open your PDF document in Preview and click the **Show Markup Toolbar** button—it looks like a little toolbox near the top of the window. Once the toolbar appears, locate and click the **Sign** button, which resembles a signature line with a pen.
2. In the signature popup, select **Trackpad**. Use your finger to draw your signature on the trackpad. Press any key when finished, and you will see a preview of your signature. If you’re not satisfied, tap **Clear** to try again. When happy, click **Done**. Your signature now appears in the popup and is saved for reuse.
3. If you prefer using pen and paper, select the **Camera** option in the signature popup. Sign your name clearly on a white piece of paper, then hold it up to your Mac’s camera. Preview will detect the signature and display it on screen. Adjust as needed, and click **Done** to save.
4. To create a signature using your iPhone or iPad, choose the **iPhone or iPad** option. When prompted, your device will open a signature capture screen where you can draw your signature with a finger or stylus. Once completed, it will transfer automatically to Preview and save for future use.
5. After creating your signature via any method, you can easily insert it into PDFs by clicking the **Sign** button and selecting your saved signature. This signature remains available for all documents opened in Preview.

By following these steps, you build a reusable handwritten signature in Preview that fits your preferred input method. This setup streamlines signing tasks and avoids the need to scan or print documents.

## Sign a PDF document with your saved signature in Preview

1. Open your PDF in Preview and click the Markup Toolbar button (the pen tip icon) to reveal annotation tools. You should see your saved signature icon among the options.
2. Click the signature icon to select your saved signature. Your cursor will change to display the signature ready to place on the document.
3. Navigate to the page where you want to add the signature, such as the last page of a multi-page contract. Click once on the desired location in the document to place the signature. The signature will appear, but it may need adjustment.
4. To resize the signature, click on it to reveal blue handles at the corners and edges. Drag these handles inward or outward to make the signature smaller or larger until it fits the signature field or space appropriately.
5. To move the signature, click and drag it to the exact position required. This allows you to align it precisely within any form fields or designated signature areas.
6. If you need to add the signature to multiple pages, repeat the placement, resizing, and moving steps on each page where signing is required.
7. Once satisfied with the signature placement, choose File > Save As to save the signed document under a new filename (for example, "Contract\_Signed.pdf"). This preserves the original unsigned PDF and securely saves your signed version.
8. Verify your saved PDF by reopening it in Preview to confirm the signature appears correctly on all intended pages.

## How to digitally sign a PDF in Preview on Mac

A digital signature is a cryptographic method that verifies the authenticity and integrity of a document. It uses a digital certificate issued by a trusted certificate authority (CA) to confirm the signer's identity, providing a higher level of security than a handwritten signature. Digital signatures are often required for legal, financial, or official documents where proof of signer identity and tamper-evidence is critical.

Preview on Mac primarily supports adding handwritten signatures and does not natively support applying certified digital signatures with cryptographic certificates. If your document requires a certified digital signature, you will need to use third-party software such as Adobe Acrobat Pro, DocuSign, or other specialized digital signing tools that support certificate-based signatures.

For documents that do not require certificate-based validation, a handwritten signature created and placed in Preview is usually sufficient and legally accepted in many contexts. Understanding the difference helps you choose the right signing method for your document’s purpose.

| Signature Type                         | Legal Validity                                                         | Trusted Authorities                   | Use Case                                                           |
| -------------------------------------- | ---------------------------------------------------------------------- | ------------------------------------- | ------------------------------------------------------------------ |
| **Handwritten Signature (in Preview)** | Generally accepted for most informal contracts and documents           | None needed                           | Quick sign-offs, internal documents, personal agreements           |
| **Digital Certificate Signature**      | Strong legal standing in regulated industries and government documents | GlobalSign, DigiCert, Entrust, others | Financial contracts, legal filings, regulated compliance documents |

If you need to apply a digital certificate signature on a PDF, follow these steps:

1. Open your PDF in a third-party app that supports digital signatures, such as Adobe Acrobat Pro. You should see an option like "Certificates" or "Digitally Sign" in the toolbar.
2. Choose the digital certificate you want to use. This will typically be installed on your Mac or provided by your organization.
3. Click the area in the PDF where you want the signature to appear. The app will prompt you to confirm the signature using your certificate.
4. Once signed, the PDF will display a signature panel or icon indicating the document is digitally signed and verified.

In summary, use Preview for quick handwritten signatures, and switch to dedicated digital signing tools when certified digital signatures are required.

## Send a PDF for signature using Preview

After signing your PDF in Preview, you might need to share it with others for additional signatures or review. Preview allows you to export the signed document easily and send it via Mail or other apps on your Mac. However, Preview itself does not support multi-party signing workflows or tracking signature statuses like dedicated e-signature services.

![Send a PDF for signature using Preview – how to sign a PDF in Preview](https://macfixly.com/content/images/2026/10/sign-pdf-preview-mac-3.webp)

1. Click **File** in the menu bar, then select **Export as PDF...**. A dialog will appear to save your signed document.
2. Choose a location and filename, then click **Save**. Your signed PDF is now ready to share.
3. Open the **Mail** app or your preferred email client on Mac.
4. Compose a new message and attach the signed PDF by dragging it into the email window or using the attachment button.
5. Use a clear subject line like *Document for Signature* and include a message asking the recipient to sign and return the document.
6. Send the email to the intended signer. They can open the PDF in Preview or another PDF app to add their signature.

Here is an example email template you can use:

> Subject: Document for Signature  
>  
> Dear \[Name\],  
>  
> Please find attached the document that requires your signature. Kindly review, sign, and return the completed PDF at your earliest convenience. If you have any questions or need assistance, feel free to reach out.  
>  
> Thank you,  
> \[Your Name\]

While Preview enables easy sharing of signed PDFs, it lacks features like signature requests, reminders, and verification tracking offered by specialized e-signature platforms. For workflows involving multiple signers or legally binding digital certificates, consider services such as Adobe Sign or DocuSign, which streamline sending, signing, and managing documents securely.

## Troubleshoot common issues with signing PDFs in Preview

If Preview does not display your PDF correctly or won’t open the file, first check the file format and integrity. Preview supports standard PDFs but may fail with corrupted or password-protected files. Try opening the PDF in another app like Adobe Acrobat Reader to verify the file. If it opens elsewhere but not in Preview, restart Preview or your Mac to clear temporary glitches.

If the signature tool is missing or not working, ensure you are in the Markup toolbar by clicking the pen icon in the Preview window. Sometimes the toolbar might be hidden—show it by selecting **View > Show Markup Toolbar**. If the signature option still doesn’t appear, update your macOS as older versions might have limited Preview functionality.

When signed PDFs do not save or changes do not reflect, it usually means Preview’s autosave isn’t functioning or you are working on a copy without saving. To fix this, after placing your signature, choose **File > Save** explicitly. If you saved a duplicate, check that you are opening the right file afterward.

For issues with digital signatures or certificate validation, Preview itself does not create certified digital signatures. If you receive errors opening digitally signed PDFs, verify that you have the correct certificate installed and trusted in your Keychain Access. Some certificates require third-party apps to validate properly.

If you use Windows Preview or other OS preview apps and PDFs do not show or sign correctly, the problem is app limitation. Windows default PDF viewers often lack advanced signing tools. Consider using dedicated PDF software like Adobe Reader or third-party apps with signing features for consistent results.

1. Open the PDF in Preview; if it fails, try another app to confirm file integrity.
2. Show the Markup Toolbar via View > Show Markup Toolbar; check for signature tool availability.
3. Place your signature, then go to File > Save explicitly to ensure changes are stored.
4. If digital signature errors appear, open Keychain Access, check certificate status, and install missing certificates.
5. For issues on non-Mac OS, switch to a PDF app with robust signing support to avoid compatibility problems.

## Frequently asked questions

### How to turn on pdf preview?

PDF Preview is the default way macOS opens PDF files using the Preview app. To ensure your PDFs open in Preview, right-click a PDF file, select "Get Info," then under "Open with," choose "Preview.app" and click "Change All." This sets Preview as the default PDF viewer, effectively turning on PDF preview for all PDF files.

### How to sign in a pdf?

To sign in a PDF, you generally need a tool that supports adding signatures, such as Preview on Mac. You can create a handwritten signature using your trackpad or camera, save it, and then place it anywhere on the PDF. Alternatively, digital signatures that use certificates offer stronger verification but require a supported signing tool.

### How to sign in a pdf document with preview?

Open your PDF in Preview, click the Markup toolbar button, then select the Signature icon. Choose to create a new signature using your trackpad, camera, or iPhone. After saving, click your signature to insert it into the document and move or resize it as needed before saving the file.

### How to sign pdf on computer with mac preview?

Launch Preview and open your PDF file. Click the Markup toolbar, then the Signature icon. Create or select your saved signature, click to place it on the PDF, adjust its size and position, and then save the document. This method is quick and does not require additional software.

### How to preview pdf?

To preview a PDF on Mac without fully opening it, select the PDF file and press the spacebar to activate Quick Look. This provides a quick view without launching Preview. For detailed interaction, double-clicking the file opens it in the Preview app where you can read, annotate, and sign.

## What This Guide Does Not Cover

Preview does not fully support certified digital signatures that some legal or corporate documents require. If you need to add a legally certified digital signature, consider specialized digital signature software designed for that purpose. This guide assumes you are using a Mac with the Preview app and does not cover signing workflows on Windows or other operating systems. Additionally, handwritten signatures created in Preview are image-based and do not provide cryptographic security, so they may not meet all security or compliance requirements.

The most useful next step is to practice creating and applying both handwritten and digital signatures on sample PDFs to become comfortable with Preview’s tools. This hands-on experience helps you avoid common pitfalls, such as saving your signature correctly and positioning it precisely, ensuring your signed documents look professional and are ready to share quickly.

**See also:** [How to Export Notes to PDF in the Notes App: A Step-by-Step Guide](https://macfixly.com/p/a7ae047c-1483-494d-9047-fd8a524a5eae/) · [How to Export Emails to PDF in Mail App: Step-by-Step Guide](https://macfixly.com/p/3c3f69a2-83b6-44c6-b6c3-6ee6feba9ba2/)