[mikesears]

Under NFHS rules, all A players are prohibitted from going out of bounds and returning during the down unless blocked out by an opponent. If blocked out, the A player must make an effort to return immediately. If he goes out on his own (accidentally or intentionally), the foul is illegal participation and the spot of the foul is where he returns.

He is still eligible to receive a pass regardless of how he went out of bounds. (i.e. There is no illegal touching if he is first to touch a forward pass after going out of bounds on his own)