back on topic:
I added the code to the user's profile Contact Info tab
Code:
Open template: memberinfo_block_contactinfo
FIND:
<dd><a href="$prepared[profileurl]">$prepared[profileurl]</a></dd>
AFTER, ADD:
<dt class="shade">Referrer ID</dt>
<dd><a href="$vboptions[bburl]/index.php?referrerid=$bbuserinfo[userid]">$vboptions[bburl]/index.php?referrerid=$bbuserinfo[userid]</a></dd>