  We extend the renormalized quasiparticle description of the symmetric
Anderson model in a magnetic field $H$, developed in earlier work, to the
non-symmetric model. The renormalized parameters are deduced from the low
energy NRG fixed point for arbitrary field values. We find quasiparticle
resonance widths, $\tilde\Delta_\sigma(H)$, which depend in general on the spin
$\sigma$ as well as $H$. The low temperature static properties can be expressed
completely in terms of these parameters, which can also be used as inputs for a
renormalized perturbation theory. We show that taking into account repeated
quasiparticle scattering gives results for the longitudinal and transverse
dynamic spin susceptibilities which are in very good agreement with those
obtained from direct NRG calculations.
