At Oat Foundry in Bensalem, makers of split-flap boards similar to the old-fashioned one announcing arriving and departing trains at Philadelphia’s 30th Street Station (which Amtrak plans to remove), revenue is on a fast track. To handle even more expected expansion, the company of seven employees plans to add three to five more over the next year, said CEO Mark Kuhn., one of six founders. As engineering majors at Drexel University when they started the company five years ago, they weren’t trained on hiring, Kuhn said.