We prepare financial statements and sometimes we need to find the source of
the information for certain items on our reports. Is there a way, other than
inserting comments, to insert a footnote that appears on the side of the page
(like on the left margin). We don't want it to print but my boss likes to
see the source of information as he scrolls down on the document.

A feature similar to bookmarking feature on Adobe Acrobat.