great.....rm is a canadian brand, and will naturally have a big following there.....plenty of love for them this side of the pond though too....the price you get wont differ greatly, but postage to the states or canada could offset the cash you get for it
a frame number will imply honesty, and allow the frame to be identified in another manner other than paintjob.....if you have knowledge of its history then i would briefly list it, but dont go ott with it.......list its faults, and back them up with pics if you deem it neccessary. a potential buyer wouldnt expect it to never have been ridden, and a little 'patina' is all part of a bikes history, and celebrated in these parts rather than avoided.
present what you offer openly, and let the buying public make its mind up. a poorly described bike will likely bite you on the arse at a later date when the person who buys it lodges a complaint with you/ebay when the unridden golden goose you described turns out to be a weather beaten pile of crap!.....
catalogues are in the archive here.....get an accurate year for it to avoid looking vague and like you are trying to cash in by selling a lost uncles cast offs that you know nothing about.....
....you do also have the option of keeping it and riding it with us reprobates.....the memories you will create will outstrip its cash value!