The kidney reflex is located just below the ball of the foot in the center of the foot and is shaped like a kidney bean.  It is approx 1 inch wide by 1.5 inches long.  You stimulate it by pressing into it.  Use your thumb to press firmly into various parts of the area until you cover the entire reflex.  Some reflexologists will rub it vigorously.  I would also stimulate the ureters and bladder reflexes to encourage the exit of the stone fragments.

Be well,

Cheryl L. Sneed, LMT