We present a theoretical study of the surface spin-flop transition which oc
curs in Fe/Cr multilayer films. The low-frequency response is effectively r
educed to the dynamics of an antiferromagnetic discrete sine-Gordon equatio
n due to the strong demagnetizing field created by out-of-plane fluctuation
s. We thus carry out a detailed calculation of dynamic susceptibilities whi
ch confirms and completes earlier theoretical work, and may suggest further
experimental investigation of some of the more intricate aspects of this s
ubject.