If you’re sent a PDF of a form or document by email, and you need to sign and return it, it’s much easier to sign it on your Mac and send it straight back than it is to print it out, sign the printout, and then scan it back to your Mac. Keep on reading, and we’ll show you how you can do that.

How to sign PDFs on your Mac

If you have Adobe Acrobat Pro, you could use that to sign a PDF on your Mac. But most of us don’t, so we’re going to show you how to do it using Preview.

Tip: Keep your Mac running smoothly

Working with large PDFs, especially those with high-resolution images, can put a strain on your Mac, especially if it’s an older model. One way to minimize the effects of that is to keep your well-maintained. Just like a car, a Mac that’s properly maintained runs longer and more smoothly. That maintenance includes reindexing Spotlight, freeing purgeable space, and repairing disk permissions. And while you could do that yourself or use several different tools, it’s much easier to use one application to do everything. We recommend CleanMyMac. 

Its Performance feature can do all of those tasks, as well as thin out Time Machine snapshots, flush DNS cache, and more. The best part? You can test it for free 7 days — get your free trial here. 



Start by filling in the form

  1. Launch Preview and open the form you want to sign.
  2. Click the Pencil icon and then the form button in the toolbar (a rectangle with dots across it).
  3. Click in the boxes on the form and type in your details.

Sign the PDF

  1. Click the signature button in the form filling toolbar (a squiggly line).
  2. Choose Create signature.
  3. You now have a choice of how to create the signature

Sign a PDF using the trackpad

  1. Choose Trackpad.
  2. Click on the signature box.
  3. Use your finger to write your signature on your Mac’s trackpad. If your trackpad has force touch, you can press down harder to make the ink darker.
  4. Click Done when you’re finished or, if you don’t like your signature, click Clear and start again.

Sign a PDF using your Mac’s camera

  1. Click the camera icon.
  2. Write your signature on a piece of white paper and hold it up to the camera.
  3. Make sure your signature is level with the blue line.
  4. When your signature appears in the window, click Done. Or, if you don’t like it, click Clear and start again.
Tip: Optimize your Mac’s performance

We talked earlier about how important it is to keep your Mac free from clutter. That’s one element of optimizing your Mac and helping it run as smoothly and quickly as possible. However, there are several other things you can do, like reduce the number of services that run at a startup, quit applications that have hung, and keep track of applications that are using lots of resources. You can do all of that very quickly and easily using CleanMyMac’s Performance feature mentioned above and the Menu App. You can open it by clicking a little iMac icon in the menu bar.

If you use these two tools regularly, your Mac will continue to run smoothly for a long time to come. Get started with a free CleanMyMac trial — check out how these and other features work for 7 days free.


Sign a PDF using your iPhone or iPad

  1. Click Select Device.
  2. Choose the device you want to use.
  3. Sign your name with your finger on your iPhone or iPad.
  4. If you’re happy with the result, click Done. If not, click Clear and start again.

Every time you click Done, the signature you created is saved so that you can use it again. And you can save multiple signatures, and each time you need to sign a PDF, choose the one you want.

  1. Click the signature button.
  2. Choose the signature you want to use.
  3. Drag it to the place you want it on the page.
  4. Use the handles to resize it so that it fits the space.

There are lots of ways of signing a PDF in Preview. You can use your Mac’s trackpad, camera, or even the screen of your iPhone or iPad. Follow the instructions above for whichever method you want to use.