Adding stubble to a map?

Upirium

I want to add some stubble to one of my texture maps
The character I'm trying to create has light stubble but not extreme.
I try using one click facial hair but it has problems and it's not exactly what I want and doesn't pattern in the right way.
I guess I could just use a stubble brush or something but I'm wondering if there's any merchant resources that can fit on the specific mats for m4...
I don't know how to describe it other than that.