In the R-logic dialog, you can set the number of the R-sites to be occupied in the Occurrence field. If the Rest H condition is set for an R-group, that means that the hit molecules do not contain ligands on that atom other than hydrogen or those specified as R-group.
R-logic dialog is available through Empty space context menu, R-group definition context menu, and by right-clicking the R-group label in the scaffold structure.
Valid values for Occurrence:
Exact numbers, for example, 2
Less than (>) + number, for example, <4
Greater than (<) + number, for example, >1
Range, for example, 2-3