Do you mean rakeback offers or do you mean rake in terms of how you earn it for rewards. Rake in and of itself is just a percentage of the pot paid to the house.
There are three main types of rakeback or rake rewards offers in online casinos
that are used. But of course, there may be certain exceptions at times and some casinos may have slight variations of their own. Anyways, the three main types are:
Dealt: The rake is split between all players on the table. With this method, you don't even need to be in the pot, you just have to be dealt on hand. Obviously, this is great if the pot gets large and you fold early - but on the other hand, if you're involved in a large pot, regardless of if you win or lose the pot, the rake on it is going to be split with everyone. So whether that's a pro or a con is entirely based upon when and if you folded and how big the pot is.
Contributed: In a lot of ways, I kind of see the contributed method as a bit more fair because it only calculates your rakeback in terms of how much you actually contributed to the pot.
Shared: In the shared method, everyone receives a portion of the rake based upon their involvement in the hand, which is that they've purposely put money in the pot. So blind bets aren't involved in this method, because that's a forced bet upon a player. This type of method is sort of a middle ground between contributed and shared because only people who have voluntarily added money to the pot can earn rakeback; however, everyone shares it equally not just based upon a percent of each person's bet.
Again, these could vary from casino to casino, so you hsould check and see what method you're uses.