I see people on these forums who max out at a few hundred micrograms, others who take 10-30 milligrams. It really depends on how you respond.
I am trying to substitute some folinic acid for the MTHF, since I don't have the MTHFR C677T, and since MTHF is so expensive. I take 5 mg of MTHF and one or two 800 mcg of folinic. I'm also taking TMG because of BHMT 08 mutation, so I figure I've got enough methyl groups hanging around to methylate the folinic acid. I have always had perfect skin even as a teenager and now I'm post menopausal, but my face and scalp broke out for several months when I was on 1 mg of MTHF. It's better but not great now, which is why I'm trying two of the folinic this week.