To Rec a response, click the actions tab under the response, and press Rec.
Rec as many responses as you like.
You can't Rec your own response (why would you even want to?), the system won't let you.
If you create accounts solely for the purpose of Rec'ing yourself. I will delete the Recs from those accounts and ban the accounts from the site. If it continues to be a problem, I'll ban your main account as well. This is for fun.
(Half point Finder's Fee goes out to Marima for this one.)