The Rayleigh-Taylor instability of a magnetic fluid superimposed on a
non-magnetic liquid of lower density may be suppressed with the help of a
spatially homogeneous magnetic field rotating in the plane of the undisturbed
interface. Starting from the complete set of Navier-Stokes equations for both
liquids a Floquet analysis is performed which consistently takes into account
the viscosities of the fluids. Using experimentally relevant values of the
parameters we suggest to use this stabilization mechanism to provide controlled
initial conditions for an experimental investigation of the Rayleigh-Taylor
instability