Rule 7-3-4 only applies to offensive players
If an offensive player does it, the official nearest throws his hat on the ground usually. Throwing the hat does not always mean the player stepped out of bounds. For example, during the Utah-Oregon game's "dumbass play of the year" the official threw his hat down indicating the fumble took place. It did not mean, as many incorrectly interpreted, that the defender who stepped out of bounds could not recover the ball.