All-Pro tight end George Kittle has agreed to a five-year, $75 million extension with the San Francisco 49ers that is the richest contract ever at the position. A person familiar with the deal says the sides agreed on the deal to keep Kittle off the market next offseason. The person spoke on condition of anonymity because the contract hadn’t been announced by the team. NFL Network first reported the terms and says Kittle will get an $18 million signing bonus.