Is it possible to display a radiobutton with two text lines?

There is no way to specify a two-line text in the radiobutton command. What you can do is to display a separate text line, e.g.

Radiobutton (10,1) "Text...."  name= ...

Text (11,3) "Further text line"

But when the user clicks on the second textline, the radiobutton state is not changed.