BK, thanks for the info, so in Harrahs system, RFB, just means maybe for some stuff--unless you play a lot!
In Vegas, that is correct;
In Atlantic City, you are pre-qualified for a certain level of RFB; and when you charge back to your CET-property room-folio the computer determines how much it is going to pick up (usually 100%, if it's only 2 people and "reasonable" charges).