In Touch Meaning

(rugby, of a ball or a player) outside the playing area or touching the touchlines of the playing area.

Example:   Let's stay in touch.
  I'm not reachable over the weekend, but I'll be in touch early in the week.
  How can I get in touch with her? It's urgent.
  Don't be a stranger. Keep in touch.
  Kick the ball in touch.
2011 September 18, Ben Dirs, “Rugby World Cup 2011: England 41-10 Georgia”[1], BBC Sport:
  And when scrum-half Ben Youngs, who had a poor game, was burgled by opposite number Irakli Abuseridze and the ball shipped down the line to Irakli Machkhaneli, it looked like Georgia had scored a try of their own, but the winger's foot was in touch.