I used two lenses on the Hexar RF; the CV-90/3.5 APO Lanthar and the non-rf coupled CV25/4 Color Skopar.
Both gave perfectly sharp pictures at all apertures. Of course, with the 25 there's a bit of guesstimation involved, but with the 90mm the RF was spot on..
The only caveat with the CV-90/3.5 is that the 90mm framelines are so small in the 0.6x finder that framing is a bit hard, especially with regards to keeping things horizontal/vertical.