Foxit PDF Editor adds PSI support for free-form annotation. You can use Surface Pro Pen or Wacom Pen to add free-form annotations with PSI in PDFs. Detailed steps are as follows:
- (For Surface Pro users) Choose Comment > Pencil, and then add free-form annotation as needed with Surface Pro Pen;
- (For Wacom tablet users) Connect your Wacom tablet to the computer, choose Comment > Pencil, and then add free-form annotation as needed with Wacom Pen.