Yes, possibly it will be a problem. Fill it up, like Pat says, and hope for the best. You could also use a mixture of wood glue and sawdust. It would have been a good idea to leave enough wood around the knot on the width to compensate for it. I assume that's a belly view so there is no way to leave extra wood on the belly except when you tiller leave that area alone. When you tiller try to not allow that knotted area to bend too much. It should appear flat. Jawge