Here's the rule, it's pretty clearly skates.
A player is on-side when either of his skates are in contact with the blue line, or on his own side of the line, at the instant the puck completely crosses the leading edge of the blue line. On his own side of the line shall be defined by a “plane” of the blue line which shall extend from the leading edge of the blue line upwards. If a player’s skate has yet to break the “plane” prior to the puck crossing the leading edge, he is deemed to be on-side for the purpose of the off-side rule.