Rakeback

[VA Poker]

Can anyone explain how rakeback works? I've played on multiple sites that offer it but have never known how to take advantage of it. I've tried to find info from different sites and it seems like you have to go through some kind of third party in order to get RB. Is that the case? If so, do you have to pay that third party? If anyone knows it would be greatly appreciated, I get the feeling I'm missing out on alot of money considering I play relatively high volume.