In modern business environments, printing out a contract, signing it with a pen, and scanning it back into your computer is an outdated and inefficient workflow. If you use an Apple computer, you might assume you need to purchase expensive third-party software like Adobe Acrobat to handle digital contracts. However, learning how to sign a PDF on Mac is entirely free and built directly into the operating system’s native Preview application.
In this comprehensive guide, we will walk you through the technical steps of capturing your real, physical signature and applying it securely to any PDF document, saving you significant time and administrative hassle.
Are Digital Signatures Legally Valid?
Before modifying legal documents, it is important to understand the validity of what you are doing. Under most international laws (such as the eIDAS regulation in the UK and Europe, and the ESIGN Act in the United States), a digital signature carries the exact same legal weight as a wet-ink signature. By using Mac’s Preview app to insert a digitised version of your actual signature, you are creating a legally binding acknowledgement of the document.
How to Create Your Digital Signature in Preview
Apple provides two highly effective methods for capturing your signature directly within the Preview app. You only need to do this once; your Mac will securely store the signature in your keychain for future use.
- Double-click the PDF document you need to sign. By default, it will open in Preview.
- Look at the toolbar at the top of the window and click the Show Markup Toolbar button (it looks like a small pen tip inside a circle).
- Click the Sign button (it looks like a small cursive signature).
- Click Create Signature.
You now have two primary options for capturing your handwriting:
Method 1: Using the Trackpad
If you select the Trackpad tab, your Mac’s trackpad will essentially turn into a drawing tablet. Use your finger or a compatible stylus to physically write your signature on the trackpad. Press any key on your keyboard when you are finished, and click Done to save it.
Method 2: Using the Camera (Recommended)
If you want the most authentic, professional-looking result, we highly recommend the Camera method. Select the Camera tab. Take a piece of blank white paper and sign your name using a thick black pen. Hold the piece of paper up to your Mac’s webcam. Preview will automatically scan the paper, isolate your black ink, and digitise the signature perfectly. Click Done to save it.
How to Apply the Signature to Your Document
Once your signature is saved in the system, applying it to any future contract takes only seconds.
- Open the PDF in Preview and click the Show Markup Toolbar button.
- Click the Sign button. You will now see your previously saved signature in the drop-down menu.
- Click on your signature. It will appear in the centre of your PDF document.
- Click and drag the signature to the correct signature line on the contract.
- Click and drag the blue handles on the corners of the signature box to resize it, ensuring it fits naturally on the line.
- Save the document (File > Save or Command + S).
Frequently Asked Questions
Can I delete a signature if it looks messy?
Yes. If you are unhappy with how your signature looks, click the Sign button in the Markup toolbar, hover your mouse over the signature you want to remove, and click the small X that appears next to it.
Does this sync with my iPhone and iPad?
Yes, provided you are signed in with the same Apple ID across your devices and have iCloud Keychain enabled. A signature created on your Mac will automatically be available when marking up documents on your iPad.
By leveraging the built-in capabilities of macOS, you can streamline your administrative workflows and eliminate the need for printing paper entirely.
