My users complain about the buyers giving feedback in the comment field instead of opening the sellers profile and give feedback there. I have had to manually copy the comments into the database to fix this.
The feedback option is not visible when browsing the ads, just a link in the user name.
I would suggest that a more visible and direct link to feedback is shown when a buyer is browsing the ads.
Example: See my feedbacks
Place along with "See all ads from this seller".