With the center of pressure on the rudder above the aircraft CG there is an adverse roll induced by rudder deflection. That is, right rudder puts a force on the tail which pushes to the left. But, it pushes above the centerline of the fuselage so that there is an induced roll to the left. Right rudder > left roll and vice versa. Dihedral, on the other hand, induces a proverse roll. In the case of a yaw to the right, the dihedral induces a right roll. So, the idea is to balance the adverse roll induced by the rudder with the proverse roll caused by the dihedral. If the two are matched correctly, you get a pure yaw with no roll either way. That is the goal. There are clear interactions between the amount of dihedral and the design of the rudder. Also, as mentioned in another post, there can be an interaction with the anhedral in the stab (if any).

Jeff