You seldom need much gas in reverse - reverse is a very low gear and the engine's tickover revs are often good enough to get you moving. If you feel it goes too fast for comfort in reverse without you pressing the gas pedal the tickover (idle) revs may be a little too high - I think they're usually set to 750 rpm or so on most cars - if you have a rev counter check it out.
Good luck...
Peccavi
November 2009