Adding the ball of foot to a rig I'm following a tutorial: link, using Blender 2.79, but in my rig I don't have the ball of foot.

Since my purpose is to move the body delicately, I wonder if adding a bone for the ball of foot is necessary.

How can I add a ball of foot to my rig?
You need to go to Edit Mode, right click on the big ball under the ankle, press E and make another bone.