Annotate PDFPosted: December 5, 2011
The small note taking application Xournal, included in the standard Ubuntu repositories, can be used to very easily annotate PDF files.
Just select “Annotate PDF” command from the “File” menu. It will load the PDF for you to draw onto. Later use “Export to PDF” command also on the “File” menu to output everything to a new PDF file.
You may prefer using Inkscape for this, if it is a single page PDF document. Just import it into Inkscape.