Stokes V/I profiles as a function of wavelength, for the spectral ranges centered on the K I D₂ (left panels) and D₁ (right panels) lines, respectively. Upper panels: an LOS of μ = 1 is considered in the presence of a 200 G vertical magnetic field. Lower panels: an LOS of μ = 0.2 is considered in the presence of a 200 G horizontal field with azimuth χ_B = 0°. The results of RT calculations considering an atomic model with HFS (black solid curves) are compared to those obtained through the magnetograph formula, in which the effective Landé factors were obtained without accounting for HFS (red solid curves). The values for the D₁ and D₂ lines are shown in the corresponding panels.