Correct me if I am wrong, but if the batting foul is declined, R can take the ball at the spot of first touching.
If the penalty is accepted (and first touching no longer applies) it could be a tack on, but since the kick never ended and the result of the kick is a touchback, the penalty is enforced (tacked on) from the 20.
If it is an IW, then that is an IW during a loose ball and there should be a re-kick.
Fire away.