Colleen used to flick the top string with the ring finger of her left hand and I believe she had a bit of rubber stuck to the frog of her bow so it wouldn't scratch the top of her violin.
Leo Ready played it too and I never saw any scratches on his fiddle so maybe he had something on the end of his bow too.
If you are wearing finger picks, they would work just as well for your right hand and the left hand bit is easy.
Robyn