Crazy Baserunning - How do you handle?

[cshs81]

FED game. R1 R3 0 outs. Coach has R1 take off out to RF prior to the pitch hoping to draw a balk . The pitcher does not balk. The runner is now in RF.

Lets disregard the runner on 3rd for this discussion. Does the defense have to go out to RF to tag the runner out? I assume they do. I see nothing in the rulebook other than the 3 feet rule when making a play on the runner.

Thanks