Here is the recipe Baked, and you can scale it up or down based on how much you need:
5g citric acid
500ml distilled water
10 pipette drops dish soap
Mix well and spray, preferably first thing in the morning before the sun will be on the plant. If not, late in the day so it can evaporate before nightfall but not burn in the heat of the day.
Make sure you get the whole plant as PM can hide between the buds and the branch.
I've gotten some questions on the pipette drops of soap, so I measured what that works out to for a 1500ml batch: just under 1ml soap for 1500ml of water. I don't make any less but you can do the math.