How do I fix this rust area underneath the water and ice dispenser?

Dennis....Purchase some appliance paint since you have already sanded and cleaned it and spray it. Tape anything off that you need to but this should work for you.

You would lightly sand the spot then get some paint the same color and paint it

Use rustolium

Well, first why did this happen. The appliance should have been manufactured in such a way that this should not have happened. But beyond that, sanding, primer and paint with appliance paint should do the trick.

I agree with Sharon. From the look of the photo, it appears there may be a leak somewhere underneath the tray and the water is slowly working its way down to that area and bubbling the finish/rusting the metal. You can try painting it as suggested above, but my guess is without solving the underlying problem, the rust spot will come back.

before you paint, apply a rust converter that comes in spray or brush on. It will prevent some of the return of the rust. I also agree with others that there may be some kind of problem creating that particular spot. Although I have had rust on the door of a freezer which was simply caused by humidity in the basement where it is located.

We had the same sort of problem on our fridge and my husband sanded and spray painted the area. Perfect match on the paint...and I'm really picky. The repair held up for years. Yes, the appliance should have been better designed/manufactured but by the time these problems appear the warranty is long gone. We finally changed out for stainless.

It's also possible that the area kept getting wet. I haven't had the same problem with my water dispenser, but, did with my washing machine, and there was no leak. I removed the plastic tray on my water dispenser because my water bottles didn't fit. I have spilled water but, have been careful to wipe it dry. My washer was due to humidity. Most dispensers have a removable "stage" or fake drainage area (it doesn't really drain). It makes sense that if water sat in that area, it could cause problems in a weak area of the finish, like on my washer. Just my two cents. If it is that causing the problem, a careful fix and keeping the area dry should resolve it.

I have the same problem with mine. My Samsung fridge doesn't have a removable tray. So, honestly, it seems like it's a design problem with Samsung. I've had water/ice dispensers in other fridge models and never had this issue before.

You will need to sand this as smooth as possible and then touch up with appliance paint to match.