Foren / Cotonti / Support / How to limit RSS feed output

I have found many people use the RSS feed of my Genoa website. I am of course very happy with that however, this has a downside.
There are websites out there who are fully streaming my content without really doing their best to indicate the content is from my website and what is even worse they stream this content into their Facebook and Twitter accounts so they get followers and readers for my content without them doing any work themselves.

I don't want to remove the RSS feed all together since hundres of people use it, I just want to limit output. I have been going through the rss.php but have not found any reference where the max number of characters to be outputted can be added.
I noticed other CMS'es have an option to set max character output of their RSS feeds but to my knowledge thats not the case for the default Cotonti RSS feed?

Anyone here knows how I can make it so the RSS feed outputs like (for example) 60 characters and than automatically generates a "read the full article here" (linking to my website) to direct the readers to my website?

This way even if those sites keep streaming my RSS feed to their social sites their readers will soon be annoyed enough to have to go from site to site to read the fulll article they will instead follow/register on my own social sites, right?