The paint itself will be the rust protection, provided that you've prepared the surface well before priming, and that you've got good coverage.
The whiteknight paints are an enamel and really easy to apply. Just take your time and do lots of light coats, you want to avoid runs at all costs. Enamel will take a lot longer to flash off than acrylic so it's easier to get some runs if you're a little heavy fingered on the aerosol or spray gun.
The can will have guidelines on how long to leave between coats, follow that and keep em nice and light and it'll look sweet. There's no cutting and polishing with enamel, so when you're doing your very last colour coat, you can go a little heavier just to get a nice glossy appearance and you're done.
