We have measured characteristic K x rays in coincidence with the scattered particles from collisions of hydrogenlike Ge ions with Kr atoms. The ions were first accelerated to 8.6 MeV/amu, post-stripped to H-like charge state, and decelerated to around 2.5 MeV/amu. From the measurements the probabilities for K-shell to K-shell charge transfer as a function of collision impact parameters were obtained. The probabilities show an onset of oscillations which are interpreted as quantum interference between the K-shell to K-shell electron transfer amplitudes in two spatially separated coupling regions in the incoming and outgoing parts of the collision. The probabilities of K-shell vacancy distribution created by the collision are calculated within a relativistic independent electron model using the coupled-channel approach with atomlike Dirac-Fock-Sturm orbitals. A reasonable agreement between the theoretical results and the experimental data is found.