Using 43.13.2B is always a good reference point, rarely the answer...it provides the drag formula so you can anticipate load...then you decide how to handle that...
D=0.000327 AV2 (The formula includes a 90 percent reduction factor for the streamline shape of the antenna.) D is the drag load on the antenna in lbs. A is the frontal area of the antenna in sq. ft. V is the VNE of the aircraft in mph.
Most com antennas give about 3 lbs of drag, not much. The FAA talks about doubler-plates most often for antennas and I think the advice by many above is very sound, having removed/replaced many many certified antennas over the years. In areas of thick skins, modest distances to structure (i.e. ribs, stiffeners, etc....) rarely have I seen doublers with rivet attachment, and very rarely with attachment to spars & ribs etc..... I often rivet the doubler, but that comes from having one less thing to move around when the antenna is serviced, not from a concern of structure. For what its worth. What a great process it is to build a plane!
Dues paid 2017
RV7 built & sold, 500h of pure joy in the air: sold
RV10 slow build & flying & loving it