The usual amount recommended is 1/8th teaspoon (0.5ml) each time you apply.
If after a few weeks your symptoms are not improving you may wish to try increasing the amount. There have been no reported side effects from natural progesterone so you can feel free to experiment.
Tip: an easy way to measure 1/8th of a teaspoon is as follows – Dab the underside of your little finger halfway to the nail (just as a face cream). The amount is about the size of a garden pea.