Normalised individual Fe Κα line profile contributed by the Be decretion disc assuming an extended source represented by two rings of hot plasma of radius 1.5 R_* and located 0.5 R_* above or below the Be decretion disc. The line profile is binned into velocity bins of 50 km s⁻¹ and is normalised by dividing by the total flux over the entire line profile. The spectral energy distribution of the illuminating source is an optically thin thermal plasma model with kT = 12.5 keV. The red histogram corresponds to an axisymmetric disc truncated at r = 176 R_⊙. The blue histogram yields the results for a disc with spiral extensions as described in the text and computed out to a = 375 R_⊙. The normalised profiles are displayed in velocity bins of 50 km s⁻¹.