The only thing you need for the RAF bonus is:

a) to be linked to another account which is within 4 levels of you; and
b) for both you and the linked account to be 59th or lower; and
c) for the mobs to not be grey for either account.

If you are account B, in this chain (A -- B -- C), and A is level 80, but you and C are both level 20, and facing level 18 mobs, you get RAF.