(Left) Sketch of the system configuration in femtoscopic measurements, where only the final $\mathrm{K^-}$--p channel is measured. (Middle and right) Theoretical correlation function for $\mathrm{K^-}$--p, from the pure elastic term (dotted line) to the full \CF (solid line) with all coupled-channels ($\mathrm{\overline{K}^0}$--n, $\pi$--$\Sigma$, $\pi$--$\Lambda$) included. The results are shown for two different radii, typically achieved in pp collisions (1~fm) and in heavy-ion collisions (5~fm).