Licorice, also spelled liquorice, has the distinction of containing the largest number of anti-fungal compounds of just about any herb or spice. It has at least 25 fungicidal compounds, whereas garlic has only 10 even though they're quite potent.
Besides its anti-fungal capabilities, it Supports the adrenal glands, Provides lymphatic energy, and supports the liver and proper sugar balance. Traditional herbalists use liquorice root as a general tonic and for respiratory support. It also supports the liver.
Most Chinese herb combinations use liquorice to balance the other herbs and to promote vitality. It has a reputation for helping the entire body maintain balance (particularly helpful to women who menstruate) and for promoting well-being. Liquorice contains triterpenoid saponins, flavonoids, isoflavonoids, magnesium, silicon, sodium and other beneficial constituents.
In Chinese practices, because of its antifungal action, it's often used for ringworm. You might want to open a few capsules a liquorice and add them to your foot bath, or add a splash of herbal liquorice extract, (not the flavoring agent available in your bakery aisle at the market)
You can also use the extract applied directly to the athlete's foot, applying it with again a cotton ball, or a washcloth. This could be done several times a day, and as always add a few drops of tea tree oil to help your body absorb the liquorice extracts and antifungal agents more quickly.