I just ordered a set for my Kimber 84M.Do these aluminum rings need to be reamed/lapped?I know people do it on steel rings to avoid ring marks on the scope and to knock down high spots.

Nope

any brand and style of rings and bases (other than Burris Signature or somehting else with the floating inserts) will need to be lapped for a good fit. THe manufactuing tolereances in rings, bases, and recivers means that no two combinations will ever point exactly in the same direction.