How can I supplement Vitamin A safely?

Trying out various supplements to try and find something that might help me cure my stubborn acne that has resisted three dermatologists, years of antibiotics, retin-a microsphere, benzoyl peroxide, exfoliation, eating healthy, etc.

I thought I'd try out Vitamin A because it's what accutance is derived from. Is there a way to do it safely? I don't want to damage my live through mega dosing or anything crazy, I just want to make sure I'm getting 100% of my recommended daily intake. I checked examine.com, but all they have is information on the topical form of vitamin a, tretinoin, which I'm already using.

I searched the sub but there's not much information on vitamin a here it seems.