Your feet can catch as well as your hands. You will find this trick easier to learn if you wear soft canvas shoes with a wide instep, or go barefoot. Leather shoes are a bit too hard & slippery.
Before catching try simply holding a ball on your foot. Stand on one leg. Curl your toes up as far as you can & place a ball in the small groove where your toes join your foot, the point nearest the big toe has the largest indentation. Practise swinging your leg gently, keeping the ball in place & not falling over. Also practise hopping up & down on the spot.
Drop a ball down to one foot. Don't throw it up, reach down with your hand, let go & just let it fall. Bend your leg at the knee & lift your foot up to meet the ball. Gently place your foot underneath the ball so that it touches the point you wish to hold the ball. Use your thigh muscles to cushion the fall until it stops. Once you can do this practise dropping from higher & higher up. Work up to throwing the ball into a foot catch. It is harder to make a foot catch from a higher point because the ball has more time to accelerate & needs to be cushioned much more than a low drop.
If you have difficulty foot catching from a throw you can make a Body Bounce off of your knee or opposite foot which will slow the ball down before making the catch. If you are using bouncy juggling balls you could let the ball bounce on the floor & catch it on the rebound.
Once the ball is on your foot you can either Lift it back into the pattern or just throw it back into a cascade. Keep your toes curled up & start by lifting your leg slowly then accelerating otherwise the ball will roll off your foot completely or fly off at an odd angle. Also try throwing it to & catching it on the other foot.