Need help with my new cat and resident cat

Hello, a few months ago i adopted Fidget, a female domestic, she's about 15 to 18 months old and is very comfortable in my unit.
A week ago i took in Kiba, a 10 week old male, for a trial adoption. He has been living in my bathroom most of the time, when i get home from work i let fidget outside and bring kiba out to play. I feed them together and by now they are quite comfortable being around each other, fidget used to growl and hiss when she saw him but not anymore.
However, the problem is when they play. Kiba always wants to play with her, and she seems to enjoy a chase and medium play, but i think kiba is to rough. He came from a house with a dog so he is used to rough play, and he'll jump on fidget and hold on like he did with the dog. Sometimes fidget will stand there for a bit when he does it without issue, but it always progresses into them chasing each other around hissing and spitting. Also, fidget is usually the one to move away, and kiba will stalk her. She only goes into stalk mode if he has been at it for a while.
They aren't hurting each other, after a clash they separate and act like nothing happened, but kiba is always wanting more.
I supervise them when they're together, and try to distract them with toys, and separate them when i need to.

Fidget is my first cat ever, so im not very experienced. I think there needs to be a boss establishment between them. Should i just let them go at it and sort it out? I appreciate any help you experienced cat owners can give me.

I think definitely refrain from interfering. Because he's a kitten, he hasn't learned what an appropriate level of force to use while playing is, and Fidget's going to be the one who can teach him that he's gone too far. She can defend herself just fine when she needs to, and she won't do any serious damage to Kiba either. Kiba is going to pester Fidget a lot just because he's a kitten and kittens are annoying, but Fidget's kind of a teenager herself so it sounds like she's still able to enjoy a good play session! But yeah, Kiba needs to be allowed to push Fidget to her limit so he can learn where the limit is. I know it's hard to let it happen, but it sounds like they are getting along very well and they're in no danger of causing harm to each other.