Today I taught some viola students.Some of them have problems of their right pinky from old teachers as their bad habits.This round relaxed pinky is really important to keep the bow straight, smooth bow changes and control the bow on the violin and viola to improve many bow articulations.
These photos with my viola and the bow are taken only to show you how the pinky should be on the bow.To make the pinky round I do suggest to lift it up after putting the bow on the string.Also exercises only with the bow are shown below. I call this exercise "car window wiper"!1.Hold the bow stright. 2. Straighten your right elbow and keep the position of the arm. 3. Turn the bow right and left with all fingers round.