rustoleum attains the texture by using metallic.
metallic ?!? What are you using it on? Right out of the can the "textured" nails the finish, the only issue being the degree of gloss. I'm afraid a shot of semigloss clear would tend to level out the texture.
Take the "textured" black Rustoleum paint in bright sunlight. Like it would be under your windsheild atop your dash. You will see what I mean, it reflects back at you. If it works for you great, I was not happy with it. I am just sharing my experience with the can of paint we had.
D