Most of the standing mannequins are supported by the use of a metal rod through the foot or into the lower leg (calf). Some mannequins, especially the smaller ones like children, only use the foot rod support while many, but not all, of the larger mannequins provide the choice of using the calf rod support. What this means is that you can put shoes on the mannequins, but in some cases you will need to put holes in the shoes or boots.
Keep in mind, mannequins' feet are much thicker than "human" feet to support the weight. Therefore, wait until AFTER you have the mannequin before sizing the shoes to make sure they will fit properly. Given the variations in shoe sizing, we do not quote shoe sizes for our mannequins.