  We study the resonant x-ray scattering at Si and Al K-edges from chiral
materials, $\alpha$-quartz and $\alpha$-berlinite. We derive the general form
of the scattering matrix for the dipole transition by summing up the local
scattering matrices which satisfy the symmetry requirement. The oscillation
term is obtained in the spectral intensity as a function of azimuthal angle
with an expression of possible phase shift. We evaluate the parameters
undetermined by the symmetry argument alone on the basis of underlying
electronic structures given by the bond-orbital model. The spectra are
calculated on forbidden spots $(001)$, $(00\bar{1})$, $(002)$, and
$(00\bar{2})$ in circular polarizations without adjustable parameter,
reproducing well the experimental curves depending on polarization, chirality,
and scattering vector. Some discrepancies remain in the phase shift in
$\alpha$-quartz.
