Attaching additional files. An extensive page management. Watermarking.
Image to PDF. Viewer modifications. Inserting own notes and message boxes.
Passwordsetting (user and main). Modification for all relevant PDF properties. ...And this all for a very moderate price.
OK, so you want to stamp your document. Maybe you need to give reviewers some advice about the document's status or sensitivity. This tip from author Ted Padova demonstrates how to add stamps with the Stamp Tool along with related comments.