KO - out-of-bounds rules

[clfossum]

Hello
I'm wondering if anyone can explain - what has been termed a "little known rule" - about returning a kickoff (in the NFL)? . . . (The kickoff was 'aimed' at the corner of Goal Line and Out-of-bounds line) . . If a player on the receiving team touches the ball, and then steps out of bounds - I believe it is receiving team's ball - at the spot it went out. (please correct me if wrong - and if it makes a difference if the player controls the football or just touches it). However, if the receiving player was to first step OUT of bounds, and then touch the ball (with one foot in and one foot out) . . . should the ball be placed at the out-of-bounds spot? - or, is the player now a "part" of "out-of-bounds" . . . resulting in a kickoff that went out - being placed at the 40? And / or would there be any penalty for coming in from out-of-bounds and being the first guy to touch the ball?

Thanks in advance.