I have a 2007 Santa Fe and it has a scratch on the car as indicated by the picture. If it is not too late, I would like to treat the scratch so I can prevent rust from developing on the car.

What is a good product to use to help seal or treat the car?

 

Time is ahead of you because rust has already begun.

That rust would need to be cleaned off, covered with a little primer, then fill in the scratch.
Any other method will hide the problem, TEMPORARILY , AND IF YOU ARE REALLY LUCKY WILL NOT RETURN . BY THEN YOU WILL STOP LOOKING AT THAT AREA.There are accepted ways and others to repair this.. Short cuts are only temporary..