In Groovescribe, you don’t enter rests. You just enter the drum/cymbal strikes at the points in the measure when the occur. You would select the eighth note subdivision. It would look like this (I am putting your track on just a snare to illustrate this):
I did nothing to enter the rest. Simply placing the first hit on the 2nd 1/8 note ends up creating the rest in Groovescribe.