  Calculations are made of the $K^{+}+^{12}$C, $^{40}$Ca differential elastic
scattering cross sections at the beam momenta 0.635, 0.715, and 0.8 GeV/c. To
this end the microscopic optical potential derived in the high-energy
approximation was used where existing data on the kaon-nucleon amplitude and on
the point-like density distributions of target-nuclei were utilized. The effect
of different methods of relativization was studied and shown to play an
important role. A good agreement with the experimental data on differential
elastic cross sections was obtained.
