Polly Scale Flat Finish - HELP PLEASE

Hello All,
I recently purchased a 1/2 oz bottle of Polly Scale Flat Finish (F404106).

I am now confused as to the proper usage of this paint. Am I supposed to mix this flat finish into other paints to make it flat? I was hoping this would be a flat clear paint I could airbrush on instead of using “dullcoat” in the rattle cans.

I intended to make this an alternative to using testors dullcoat in the rattle can. I would also like to know if this can be sprayed onto a cured coating of future without turning yellow.

Thanks!!!