  We have calculated the $W$-loop contribution to the amplitude of the decay
$H\rightarrow Z+\gamma$ in two different methods: 1) in the $R_\xi$-gauge using
dimensional regularization (DimReg), and 2) in the unitary gauge through the
dispersion method. Using the dispersion method we have followed two approaches:
i) without subtraction and ii) with subtraction, the subtraction constant being
determined adopting the Goldstone boson equivalence theorem (GBET) at the limit
$M_W\to 0$. The results of the calculations in $R_\xi$-gauge with DimReg and
the dispersion method with the GBET completely coincide, which shows that
DimReg is compatible with the dispersion method obeying the GBET.
