That is a fairly old device. Seems that you aren't the only person looking for info in the RM16. See here:
http://forums.prosoundweb.com/index.php?topic=76309.0 (just one of several I came across).
It seems that the R.A.M. company is no more (went out of business or was acquired). This mixer was also on the market before electronic documents were widely available. I honestly think you are out of luck, unless you could stumble across a manual on eBay.
You might sign-up to the forum linked above and seek a current owner of a RM16 to see if they have a manual. If you could locate such a person, they might make you a copy and send to you.
I wish you good luck in your search.