There are several variations of the Antahkarana symbol, here is a brief explanation of each one:
The large single symbol is more female and creates its healing in a gentle way healing the female energies of both men and women.
The smaller single symbol is more male and more direct, focused and penetrating and will heal the male energy of both men and women. Use your intuition in deciding which one to use.
The Cosmic Cross is made of seven symbols crossing each other. This represents the seven major chakras. This symbol will purify your energy and can be used to open the heart.
The square multiple symbol made of sixteen symbols will break up blocked and congested energy, and get stuck energy moving. This symbol can also scatter your energy so it is recommended that you follow its use with the single male symbol to create centering and grounding.
Source: International Center For Reiki Training