I am looking for a list of marketing/advertising agencies in the U.S.
and Canada that promote/sell software products to potential clients
and take a percentage of sales as their fee.

While we can elucidate the features and benefits of the software and
take care of brochure preparation, printing etc. we wish to leave
other forms of advertising/marketing to these agencies along with the
job of interacting with potential clients. The software product is
initially targeted for sale in the U.S./Canada and later on for sale
in other countries in Europe and rest of the world.

Thanks, in advance.
TVR