Oob ?

[Redneck Ref]

The following is a question that came up between some officials the other night.

Player A legally obtains posession of the ball near the end line. Player B ties him up creating an alternating possession throw in. In the process of getting into position to get to the ball, player B is standing with one foot on the out of bounds line. There is no foul and Player B legally and simultaneously posses the ball with Player A.

What is your call and why?

Rule Reference please.