Displaying Posts via RSS Feeds or other means

Greetings WPMUdev!

I have a plugin that allows posts to be displayed via an RSS Feed URL. I was wondering,

Where and how do I attain an RSS feed URL from a site or blog (wordpress, squarespace, etc. etc.)

If there is no indication (RSS icon) or other reference on the site, is there still a way to grab the feed link? And if not, is there an easy implementation that I could forward to the sites owner for their reference?

Much Love,
Ciro Bey