The other option is to put in a new layer and adjust the Y translate for the body of the figure down. Make the keyframe a constant and all frames will drop by the same amount.
The advantage is that if your animation has a jump it won't be flatten by dropping to ground.

Poser 5, 6, 7, 8, Poser Pro 9 (2012), 10 (2014), 11, 12, 13