an user want to add own site's rss to my site. i tell user "prove if example.com is your site".
i want to make this:

when an user want to add own site rss:

Copy and paste the HTML code to your blog
< !- - exampleid=109422342 - - >
then
After you've done that, Check if the backlink is okay

if user add the code, user can add rss
if user dont add code, user cant add rss.

how can i do? which module or modules?