You won't find one with 100% rakeback as that defeats the purpose of them hosting a program. They won't provide a service for nothing. Good luck becoming a pokerstars pro and receiving your 100% rakeback
What I like about PokerStars is there are no rakeback programs with other sites.
You get your rakeback if you play many hands on PokerStars, and that's what I do (still need to figure out how it works exactly lmao)
Only way you can get 100% rakeback is through propping deals, which usually means you're playing on small networks with little to no traffic.
You'll need to start new tables and spend most of your time playing short handed. Lot's of rules you'll need to follow as well to actually receive the rakeback, but there are programs like that around if you search for them.
You should get rakeback at full tilt. I'm pretty sure it's like 33% or something like that. I recommend playing pokerstars, and earning rakeback after you upgrade your vip status. Pokerstars is better then full tilt. More players, more tournaments, cheaper buy-ins, higher payouts.