1. Compose a new message or reply to an existing one in the Mac Mail client.
  2. Attach a PDF file to the message. MORE: Apple OS X Yosemite: Top 7 Features
  3. Click on the attachment and select Markup from the menu which appears. 
  4. Add your notes or annotations and click “Done.” You can even add your signature, if you’ve saved one (How to save your signature on a Mac).

macOS High Sierra Tips

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