KiDS North and South survey areas are shown in light grey in the upper and lower panels, respectively. The positions of ACT clusters used in this analysis are indicated by each circle. The colour of the circles corresponds to cluster redshift, with yellow indicating high redshift and black indicating low redshift. The size of each circle scales with the SZ signal-to-noise, which is correlated with the cluster mass when the noise is the same everywhere, such that larger circles represent clusters with a greater SZ signal-to-noise than smaller circles.