Just discovered this today after a little research, although I'm sure a lot of you folks already knew this. Just in case..
I wanted to add a local news/talk radio station to my Rune "Webradio" list, but it's an iHeart radio station with no apparent copyable stream address on their webpage. It appeared that you had to listen through their app or on their webpage. Not one to take "no" for an answer, I did a little searching and found something that works.
1. While on the iHeart page and listening to your station, hit Cntrl-U to open the page of code.
2. Search for "streams" , including the quotes.
3. Somewhere after that, you'll see one that says "Shoutcast." That's the one you want. Copy and paste that link, starting w/ "http:/..." etc (do not include the quote) into the address field when you add a Webradio station in Rune, and you're good to go!