Finasteride itself is useless with HRT cause it only reduces 5ar2 which would be already low due to very low levels of Testosterone. Only dutasteride can help on hrt by inhibiting 5ar1. Most ppl do good with 50% reduction that 0.5 mg(DAILY) dutasteride offer but if u want the max regrow, 2.5 mg dutasteride daily should be used to inhibit like around 80% of 5ar1 and scalp dht. I noticed high dosages dutasteride also helps with skin smoothness. When i stopped bica my skin was kinda oily and less soft but when I started high dosage dutasteride after the first month my skin started to get soft again and no oil at all.
BTW nor finasteride or dutasteride will increase libido on HRT cause the mechanism of why finasteride/dutasteride makes one hornier is due the increase of T by DHT inhibition, but with estradiol you will inhibit your T to castrate range anyways.