Formerly, the Dutch spelling of the name was (pre-1935 when the family changed it as a whole):
Fockert
And yes, some "friends" I have from the Netherlands, call me the original pronunciation, which sound decidedly exactly like what you are thinking.
We've got some serious relation in the Netherlands... many use the Fockert name in products and websites. Some are pretty large also.
Folkert is actually a *FIRST* name in the Netherlands.