Rhydderch

Um...I don't know.

I like a lot of Welsh names, and this one is no exception. I like the Y and the two D's in it. However, I tend to pronounce names phonetically (and Welsh is a hard language for me to pronounce in the first place), so if I were using it in a story, I'd probably spell it "Ridderick" or some similar spelling. I am rather fond of this name.