Hello, I am John, a Ford dealer technician.
I hope I can help solve your problem quickly and accurately.
You have two possibilities. First off you can take proof of ownership (registration) and your vin number to a dealer and they can cut you a key. Once you have that key you will need to get your truck towed to the dealer so they program the key to the truck. This is because of the anti theft system. All of these trucks have this system so this has to be done. The second possibility, and possibly the cheaper, is to go to the dealer with your proof of ownership and get them to give you the key code. Now you can call a locksmith and get them to come to you and cut and program the key. Make sure you ask around and get a locksmith the can program "PATS" keys. With this option you won't have to pay the tow charge and it should be a bit cheaper. You can also go without getting the keycode but locksmiths usually charge more if they have to hand cut the key.
If you have any more questions please feel free to ask, it's what I'm here for!
If this answer has been helpful please accept so I can recieve payment. Feedback is very
important to me so please leave accurate feedback for others to see my job performance.