In order of increasing atomic radius, this would be:
(smallest) F < N < Na < K (largest)
The Periodic Trend is to increase radius as you move down a Group and to decrease as you move across a Period . This is due to the stronger attractive force of the nuclear protons on the same-shell electrons added to an atom compared to a "volumetric" increase from additional electrons.
The groups increase in radius because both the nuclear size and the electron shells involved increase.