Several oil sprayers are suitable for use in the air fryer. The silver one on the the left is called a "Misto" sprayer and can be found on Amazon. They have less expensive Misto sprayers that do not feature the window.
The middle sprayer is an "EVO" sprayer and very easy to use. It can also be found on Amazon.
The littlest sprayer on the right was hand carried from Rome for me by a friend so it's a little harder to get ;) But it's an example of the type of spray bottle that you can use.