  We evaluate the contribution of the final state interaction (FSI) due to
single pion exchange inelastic scattering for $D^+\rightarrow \bar
{K}^{0*}\pi^+$ and $D^+\rightarrow \bar K^0\rho^+$ processes. The effects are
found to be very significant. The hadronic matrix elements of the weak
transition are calculated in terms of the heavy quark effective theory (HQET),
so are less model-dependent and more reliable.
