The dropper should have 50 at the half way mark, thats the amount i did (50mgs) i dropped back a few weeks later when i started experiencing the yellow tint in my eyesight.
i ran some s-4 and my dropper wasn't marked either (i have read that some are). it was all eyeball and guesstimation. unfortunately, there's a large margin for error with that method.
I just ran 25mg twice per day, 8 weeks. Zero sides, about 5lbs gain, great strength, muscles like rocks. I see no need to go higher and risk the eye issues, when 50 per day worked so well for me.