In this article...
...which analyzes rolling friction on a rolling ball, the author claims that the normal force on a ball rolling down an incline is given by:
Where $R_b$ is the regular radius of the ball and $R_e$ is the effective radius of the ball, which is less than the regular radius since the ball squishes under its own weight.
But I don't understand. Why does the fact that the ball "squishes" as it rolls change the magnitude of the normal force?