Are using vinegar is good to remove rust on realforce plate? its just a small rust
Yep, vinegar and a cotton swap will work fine. Any residue can be swept up with some alcohol. I did this on my Focus FK-555 which is pretty much NOS, but it had a tiny tiny scratch on the plate that had rusted, but vinegar took it right off. 
And yeah the vinegar doesn't just remove the rust but the paint too 
)
Planning on getting it repainted can someone give me some instruction on how to paint plates?
It doesn't wear through the powder coat paint though. If it's just surface rust, it should come off pretty quickly before any damage to the powder coat. :3
yep I just dump the board in the vinegar for 5 hours and yeah I damaged the paint but after I brushed it with my steel brush It became quite good!
Holy moly, that must have been some SERIOUS rust or you were just lazy.
Painting? Preparation is the most important step. Make sure the surface is clean and use gloves. Acetone or Alcohol work well to degrease a surface pretty quick IME, but you don't want to use Acetone if anything's sensitive to it on the surface you're painting. Same for Alcohol. Safest degreaser is dish soap and water. Dry it well and try not to get lint on the plate--this is why I like acetone and high purity alcohol, since they evaporate very quickly.
If you're using spray cans and want a finer texture and more even spray pattern, you can heat the cans up a bit before spraying. I put mine in front of a small heater. For a metal plate, I prefer self-etching primer as it adheres really well. SEM is a brand I would recommend here. You can just give it a coat of SEM self-etching primer in black and you'd be done.
Depending on the fineness of the paint, it can even give it an awesome sand blasted anodized look. Enamel black over the primer will probably look the closest to powdercoat, but I would just use the primer if I were you.
If you want to keep the plate bare-looking, you can use Duplicolor's Adhesion Promoter and use a clear coat to protect it or something from their Metal Cast series to give it a translucent coat of whatever color they offer. I did this with Metal Cast blue for my FAME's plate since I carefully hand brushed the top-side of the plate as I refurbished it and it looked amazing.
I wish I would have known vinegar would remove powdercoat like that, since that part of the FAME restoration process, sanding the paint off of the metal back and the plate, took 4 + hours by hand.
