I dont think it would be a good idea to earn by RSS, you must think in some new direction for monetization of your blog or site. Thousands of other best possible ways are there out on net but RSS is what you seek quality information very regarding to the point and topic so keep it ads free. Valuelinks.
I have been publishing sites for a while and I finally want to try a learn how and where money can be made from them
I guess it depends on what you mean by "earn" exactly. RSS feeds are an excellent source of content that is, by the definition of the format, meant for mass consumption. That makes them a great way to build a site or at least enhance an existing one. I have a whole network of sites that simply aggregate topic-based RSS feeds that I earn consistent money with each month (and I'm not talking about auto-blogs, just for clarification). If you're just looking to monetize an existing feed for a current blog or site you have then best of luck. Tons of companies offer contextual ads for feeds but I think most people who see them aren't the types of people susceptible to clicking on ads anyway.