How to add a featured iTunes Radio station to the stations on iOS

It only works if you add your own custom stations. When you are listening to a song that you like, press on start station from artist or song. Then that new station will have the options on: play more like this, or never play this song. :)

From the Apple website:

With iTunes Radio, you can easily share stations via AirDrop, Mail, Messages, Twitter, and Facebook. The stations you share continue to change as you tweak the mix, so your friends can listen to music that adjusts with your evolving tastes. Show off your favorite stations, or tune in to your friends’ to hear what they’re into.

So, it appears to mean that they're getting a read-only instance of your station, that updates as you update it.