Apparently RuneAudio does not accept a m3u or pls link copied directly from most webradio lists. I've run into the same issue with other media centres. Looks like most of these links from sites are actually a container for the actual link.
The following is just ONE way to do this, and will show how some links are formed, and why they don't work when you simply copy and paste them.
Right click on a webradio link (I used the m3u link) such as the one shown for PigPen Radio listed on
https://www.internet-radio.com/stations/funk/, and select "inspect".
The window appears on the right, and you will notice that the link is actually a long one, and somewhere in the middle is the actual direct link to the webradio station. In this case you're looking for
http://uk6.internet-radio.com:8213/listen.plsAnyway, you really only want the part that is
http://uk6.internet-radio.com:8213 without the last part.
This link placed into your RuneAudio will work just fine.
You can right click on the element that you're inspecting, and select copy and then select copy element, and paste this into a simple text editor like Notepad, then copy paste the link out of the middle of it.
Imsai