Keynsham1 , do a search either here or in goggle for DIY RSR finish. There is a lot of information.
Ultimately it depends on exactly what you want the final finish to look like. If you just want a quick RSR look Moneymanager is correct. Mask off so only the part of the petal you want silver is showing, scuff with a 3M pad and shoot the petal with Rustoleum bright silver.
That process will give you this look. The center is Rustoleum rattle can bright silver.
If you want a polished look or a brushed look you will first need to strip the anodize. Use EZ off in the yellow can and or a scothbrite pad in a drill/air grinder to strip the anodize. Once stripped you can finish to your liking. This one is polished.
