This is from one of my trim charts:
Knife Edge Pitch:
Fly model on normal pass, roll to knife edge, left and right, use rudder to hold model level
A. Model does not change pitch: No adjustment needed
B. Model pitches to canopy: Either move CG aft; or increase wing incidence; or mix down elevator with rudder
C. Model pitches to belly: Reverse of B;

Dihedral
Fly model on normal pass, roll to knife edge, left and right, use rudder to hold model level
A. Model does not roll: Dihedral OK
B. Model rolls indirection of rudder: Reduce dihedral
C. Model rolls opposite to rudder: Increase dihedral