An F-16 is not an ideal choice for winglets, especially at this scale, from an aerodynamic perspective. A short non-technical answer is that you likely won't notice any major differences in flight, apart from maybe some slight changes in yaw-roll coupling and maybe a slight increase in roll stability. Keep them if you like how they look, but they won't make a huge difference. As mentioned by someone else, wing fences will do a better job increasing lift, but they also incur a drag penalty for doing so.
Going more in-depth, they may very slightly improve drag and lift characteristics, but the F-16 design is not well-suited to this addition for a number of reasons. Most important is the scale of the model. At lower Reynolds Numbers, small winglets basically don't do anything significant. Winglets are also best suited for aircraft with a high L/D ratio and high aspect ratio wings. On any plane with stubby wings, the flow over the wing is going to create a fair bit of induced drag with or without the winglets. On an F-16 this is even more pronounced because the wing root extensions are specifically designed to create powerful vortices (not the same vortices as the ones at the wingtips) over the top of the wing to improve lift at high angles of attack which incurs a drag penalty. As a foam board plane with the folded-over wings and square leading and trailing edges, you'll have even more drag, so the winglets will have an even smaller impact.
Ultimately it's your plane and you know how you want to fly it, but if you don't like military style aircraft, the F-16 is better suited to conversion for high AOA aerobatics. Installing vortex generators close to the wingtips, adding large symmetrical side force generators, and programming in a flaperon mix would allow you to do some pretty insane stuff while also making your plane look a lot less military.
