How to sign, annotate, and edit a PDF on a Mac computer with Preview

Hollis Johnson/Business InsiderMac computers all come with Preview, a simple but powerful piece of photo editing software.

  • If you’re a Mac user and you’re not using Preview to view and edit PDFs, you’re missing out on a great tool.
  • Preview has the power to do much more than fill out a form. You can add pop-up notes, arrows, shapes, and more.
  • The program also has great image editing capabilities.
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Adobe Acrobat is a fine editing tool (if you enjoy being pestered with constant updates). But Mac users have a built-in alternative that comes with features comparable to the free version of Acrobat.

The list of ways you can manipulate a PDF or photo (including JPEG or PNG) in Preview is long. Here is just a sampling to get you started.

How to fill in and sign a form on Preview

This is the most basic function of a good PDF reader. In Preview, just click on the fillable sections and start typing.

You can also sign a fillable form in Preview.

1. Open the PDF in Preview.

2. Click Tools > Annotate > Signature.

Signature option in Tools menuLaura McCamy/Business InsiderYou can insert your signature into PDF documents.

3. If you’ve already added a signature to Preview, it will appear in a pop-up box. Click your signature to add it, then drag it to the appropriate spot on the form.

4. If you don’t have a signature or want to create a new one, click “Manage Signatures.” A window will appear that allows you to create a signature on your trackpad, or scan one with your camera. Once you are satisfied, click “Done” and your signature is saved.

Create signature using track padLaura McCamy/Business InsiderYou can create a signature with your trackpad, or by scanning one with your computer’s camera.

One caveat: If you save a fillable form and send it to someone who will open it in Acrobat, Acrobat may see your entries on the form. You can get around this by printing and scanning the document or by printing to PDF.

How to annotate a PDF in Preview

There are numerous ways you can edit a PDF in Preview. Most of the editing tools are found under Tools > Annotate.

You can add text, arrows, circles, rectangles, and more. To customise these annotations, click the appropriate icon on the menu above the document.

  • Change the thickness of a line by clicking the line icon. A menu of line options will drop down.
  • To change the colour of an arrow, shape, or line, click the outline icon. A colour palette will pop down. Click on the colour you want.
  • To change the fill of a shape, click the box icon. A colour palette appears. For no fill, choose the white box with a red line across it.
  • Click the text icon to change the font, size, alignment, or style of added text. To change the text colour, click the colour box on the upper right side of the font box. A colour palette will pop down.
Font colour paletteLaura McCamy/Business InsiderPreview allows you to change the colour of most annotations.

You can annotate text that’s already in the document with options such as highlight, strikethrough, and underline. Simply place your cursor on the text you want to annotate. Choose Tools > Annotate to see your options.

How to edit a photo in Preview

You can annotate a photo with the same tools you can use on a regular PDF. In addition, you can flip a photo horizontally or vertically, crop it, or adjust the size.

To change the orientation of a photo, the tools menu gives you options to rotate or flip the image. If you want to adjust the size, choose Tools > Adjust Size. Size adjustment comes in handy if your image is too large to send or add to a social media profile.

Here are the steps to crop a photo:

1. Place your cursor at one of the corners where you want to start cropping.

2. Drag your cursor until the dotted line is the size you want to crop.

Setting up cropping in photoLaura McCamy/Business InsiderSelect what you want to be saved after the crop.

3. Choose Tools > Crop. This option will be grayed out until you have set the crop area.

You can undo any of these changes in Preview by choosing Edit > Undo. You also have the option to revert to an earlier version of the image or PDF. Just click File > Revert To. A box will pop out showing you previous saved versions of the document.

Revert to menu optionLaura McCamy/Business InsiderYou can revert your PDF or picture to an earlier version.

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