Left panel: Offset in declination as a function of the offset in right ascension between the optical positions from DES or Pan-STARRS and the radio positions from RACS-low for the high-z candidates as well as the already known z > 5 radio quasars with the same flux limits. The colour of the data points reflects the peak flux density of the given source in the RACS-low source lists as shown by the colour-bar. The dashed circles represent a separation of 1, 2 and 3″. Right panel: Distribution of the integrated-to-peak flux density ratios from RACS-low as a function of the optical-to-RACS position for the z > 4 radio quasars currently known in the RACS area. The colour of the markers indicates the peak flux density reported in the RACS-low source lists. The dashed black line are the threshold used during our selection.