The fact that the RFM gives you a lateral vs longitudinal graph, probably gives away that you can be expected to calculate it.
However if there isn't a lateral arm or moment in the schedule completed by the people who weighed it what else can you be expected to do but assume it is zero when the aircraft is free of any load(s).
Make sure the RFM hasn't got the actual airframe schedule hidden in it somewhere, often in the weight and balance section.
I've got 40 R22s that I've flown in the database and only 1 has a lateral moment specified for it.