  The theory of the oscillating cantilever-driven adiabatic reversals (OSCAR)
in magnetic resonance force microscopy (MRFM) is extended to describe the
relation between an external magnetic field and a dipole magnetic field for an
arbitrary location of the single spin. An analytical estimate for the OSCAR
MRFM frequency shift is derived and shown to be in excellent agreement with
numerical simulations. The dependence of the frequency shift on the position of
the spin relative to the cantilever has characteristic maxima and minima which
can be used to determine the spin location experimentally.
