I, V and N LSD profiles (from bottom to top) obtained for HD 117207 (left panels), HD 154088 (middle panels), and HD 70642 (top-right panel). The V and N profiles were expanded by a factor of 700 and shifted upwards. The uncertainties are shown as bars at the top-left hand side of each panel. All profiles are shifted to the rest frame. The detection flag is given at the bottom-left corner of each panel. The vertical dashed lines indicate the range adopted for the calculation of the magnetic field. The bottom-right panel shows a comparison between observed and synthetic spectra for HD 117207 (top), HD 154088 (middle), and HD 70642 (bottom) in the region of the Li i feature at ~6707 Å, for which the approximate position is indicated by a vertical dashed line.