The rainbow truncation of the quark Dyson-Schwinger equation is combined wi
th the ladder Bethe-Salpeter equation for the meson bound state amplitudes
and the dressed quark-W vertex in a manifestly covariant calculation of the
Ki, transition form factors and decay width in the impulse approximation.
With model gluon parameters previously fixed by the chiral condensate, the
pion mass and decay constant, and the kaon mass, our results for the K-13 f
orm factors and the kaon semileptonic decay width are in good agreement wit
h the experimental data.