  Predictions for semi-leptonic decay rates of the tau lepton into two and
three meson final states with one or two kaons are derived, including a
discussion of K_S pi- K_S, K_L pi- K_L and K_S pi- K_L. The hadronic matrix
elements are expressed in terms of form factors, which can be predicted by
chiral Lagrangians supplemented by informations about all possible low-lying
resonances in the different channels. Isospin symmetry relations among the
different final states are carefully taken into account. The calculated
branching ratios are compared with measured decay rates where data are
available.
