There is no scientific proves that by consuming your own placenta will help to boost milk supply. https://www.breastfeedingbasics.com/qa/will-placenta-encapsulation-increase-milk-supply
To increase your milk supply, just to make sure you latch as frequent as possible to increase the supply as your body will know how to cope with the demand.
Also, try to rest as much as possible so your body can work at its best to produce more milk and you can try to take hot/warm drink to increase milk supply. This is a popular soup recipe to boost milk http://sg.theasianparent.com/fish_and_papaya_confinement_soup_recipe/