I live in New Zealand, where can I buy Potassium Hydroxide to make liquid soap?

Here is the answer to your next soap making question:

The following company specifically state that they supply potassium hydroxide in both liquid and solid form, their website link is below:

Aromatics & More

If you live a long way away from them, give them a call, I'm sure they would advise you if there are any suppliers closer to you.

More soon.

What would be a good soap recipe for oily skin?

Here is the answer to your next soap making question:

I think it best to answer this question with an excerpt from day 4 of the course:

"Oily skin requires a soap with astringent (drying) qualities, this means the use of a blend of your favorite citrus essential oils, such as Cypress, Lemon and Bergamot, and because the increased oil output from the pores, they are liable to become easily blocked, so a good cleansing soap is required, such as Coconut Oil combined with Palm Oil indicated in the recipes section."

More soon.