You can set how many points they get per $ or whatever currency you use. They can also be used to purchase ranks as you can see in the image (VIP Gold, Silver, Bronze.) You just specify how much they need to donate to get that rank. Like I have $5 for bronze, $10 for silver, etc.
Now if you are talking about ranks as in the 42 ranks they get from either earning points or hours, you
can't set that.