You'll send the RAF invite from an existing account, as in a warcraft account which can be part of the same battle net account as the others or different from the others.

When the account which you refer pays for the first month, you get a month of game play credit. And when they pay for the second month, you get the RAF mount, which I believe is now a 2-person rocket. The benefits go to the individual account which sent the referral out.