I’m quite a bit lighter then you at around 80 kg. For me, the F 93 will work with 4.5 sails quite well on flat water with small chop. If the water state gets big then 5.0 is the limit. I would say that 5.5 is the best size for my weight with the F 93.
I use a Naish Force 4.5 & 5.0 and Naish Sprint 5.5 & 6.6 with the F 93. The Sprints work better with the board but 5.5 is the smallest size for the Sprint so I use wave sails for the smaller ranges.