Rust prevention prior to painting

[disad-vantage-d]

I need to touch in a large chip on the sill seam of my 205. The chip has exposed the bare metal and is showing the very first signs of rust.
My plan is to file off the surface rust and touch in the chip with primer then paint.
Would it be better to treat the metal with a rust inhibitor prior to priming? If so, can anyone recommend a product?

[disad-vantage-d]

Thanks for the tips folks!