From a chemical point of view, mixing potassium, carbon, uranium and fluorine would result in a violent reaction where the fluorine reacted first with the potassium and then with the carbon. Small amounts of uranium hexafluoride may also be made. This assumes oxygen and nitrogen are excluded from the mixture.
The reaction between potassium and fluorine yields potassium fluoride, written as KF. This is a white crystalline solid. It's a violent reaction as it forms very strong bonds. Similarly, the reaction between carbon and fluorine forms tetrafluoromethane, also written as CF4. This is a gas, and it's known to deplete ozone. Longer chains of carbon molecules with fluorine atoms may be made in very small quantities.
The uranium reacts to form uranium hexafluoride, which is another white crystalline solid. This is often written as UF6. This compound is toxic and is a major product in the synthesis of nuclear fuel. Accidents involving UF6 have led to a number of deaths. It's unlikely that many other reactions would take place, although some exotic species may be created.
Because of the extreme danger involved in combining these compounds, special care should be taken to avoid mixing them in a factory or laboratory setting.