Line Shapes for the Radio-Frequency Size Effect in Potassium

We have measured the rf size effect in potassium using unilateral excitation of surface currents. Line shapes for both the surface reactance and resistance derivatives are obtained as a function of $\frac{H}{H_0}$, where $H_0$ is the value of the magnetic field at which the central orbit on the potassium Fermi surface just spans the specimen thickness. This value of $H_0$ has been determined independently from known Fermi-surface dimensions and the measured sample thickness. The experimental lines are compared with the line shapes calculated from Kaner and Falko's theory.