Stone chip going rusty

[Deano82]

While washing the car yesterday i noticed a small stone chip on the front lip of the bonnet which has rust in it....was quite surprised for a 2009 car!

Whats the best way to fix this? Should i just get a touch up pen and paint over it?

Cheers

 

[MrLapou]

Any car any age with chip damage down to bare metal will rust.
Need to treat the rust with a converter before touching up with paint then final layer of clear coat.