Anodizing should be obvious to the eye, but if not just try polishing a bit with some Simichrome or other alloy polishing paste. If the section of the rag with the Simichrome on it turns black, then the part is NOT anodized and you may proceed to polish it. If the rag stay clean (mostly) then the part is anodized.

I would assume the RX 100 stuff does have some type of top coat on the alloy and will need to be stripped to properly polish.