Confused about RU dosage!

[faysalnals]

In a RU guide thread here, it says "10mg of RU in 1ml is useless. Don't expect results. 20mg isnt going to do much either, so don't bother. I wouldn't go below 50mg.

Im not sure how much mg I have in 1ml though! This is the product I use: https://anageninc.com/ru58841-solution-50ml.html?ref=1

I take 1ml from the bottle and apply it to my scalp, em I doing it correctly?

Also, is it ok to get sun exposure after applying RU on scalp?