[Scribus] a bit off-topic: Tool to add notes to PDFs??

[flaco]

Hej Guys!

Does anyone out there know a easy-to-use cross-platform tool that allows to
put annotations into an existing PDF-document?

Background: I'm doing the lay-out of a magazine and there are others that
do the final checks. (far,far away.) I send the PDF to them, but until now
its kind of nasty: they have to send me texts like: "On page 3, second
column at the left border of the image text flow is nasty."

I would like to find a way that they could put a mark/note/something at
that place in the doc just saying "nasty!" (for example)
Like it was in good-old-paper-based-times: do a print, take a red pencil
and on we go. Just doing it per email.

Thanx, flacote