Johnny, Mr. Adams gave you excellent advise (get a proffessional set-up), but
you might be able to get rid of the rattle yourself. Take a small screwdriver and
loosen the center screw under the hole in the handrest a quarter turn and see if
the rattle gets worse. If so, tighten the screw gently until you feel resistance.
Then strum the strings and check for rattle. Tighten the screw an eigth of a turn
and strum until the rattle goes away or you have turned the screw one and one
half turns after you fealt resistance. Good luck.
Take care, Billy