I don't know where Duffy got it, but I have found a newspaper on-line which carried it. The one Duffy printed was from June 5, 1922. The strip was syndicated by McClure.
I can't believe how unfunny it is. I can only presume his name is Ralf because that's what you do after reading the bad gags.
If you don't have Duffy's book, there's a web site that's scanned a few of them.
http://www.barnaclepress.com/list.php?directory=RadioRalf
Here's one I've tried uploading. Don't laugh too hard.
Click HERE for a bigger image.
Jack Wilson, the artist, borrowed a take that was common in the Katzenjammer Kids, Mutt and Jeff, and probably other cartoons of that era; a character is so bowled over by the punch line, he falls with his knees up and soles of his shoes off the ground. I think Chic Young and Ernie Bushmiller used the take as well (see Ralf May 1st if you don't know what I mean).
cArtie.
