Starting ketoconzole. How much and How many times a week?

I am 22 years old and it will be 3 years in August since I have started Finasteride 1mg. This post isn't about Finasteride though. I have been loosing hair since 15 and what I have noticed that ever since I noticed my first sign of hairloss I also started extreme amount of dandruff on scalp. I also concluded that as my hairloss progressed and years passed the dandruff has got worse and worse. It was bearable in summer and worse in winter but this year it's so bad in summer that I am scared for winter. I have tried different "treatments" (mostly shitty indian remedies) like applying lemon with curd on my hair and more shit like that. Finally I have decided to go the ketoconzole route.

tldr; Only first 5 lines are relevant...other stuff is just because I like oversharing.

I have decided the brand. I am going to order a 100ml bottle. Will this last a month?

Now the question arises How much should I apply and How many times a week. I tried searching on reddit but all I am getting is confused posts. Please Help me out.