It is currently possible to export document comments in the margins of the exported PDF, by setting the corresponding *print* option.
The goal of this bug is to decide if this functionality is to be kept (then, an option should by added in the *pdf export* dialog) or if it will be removed as bug #102862
Thanks for reporting!
See bug 77650 - that has some more ideas too (not sure if that is handy BTW)
*** This bug has been marked as a duplicate of bug 77650 ***