No, I was not talking about what you said. I have had people ask if a vaulted skull told the gender of a silkie chick, since not all silkie chicks have a vaulted skull, which it does not. I have never heard of what you said before, so I can't say one way or the other if it works or not.
When looking for a good silkie, make sure it has black skin, 5 toes, and feathers on the legs outside and middle toes. The ones with a bump on the head have a vaulted skull, nothing to do with gender.