Insert threaded spacer posts beneath each exposed tile edge, making sure there is direct contact between spacer post and tile with no adhesive or mortar in between. Position spacer posts to suit tile size.
Install the adjacent tile tightly against the already inserted spacer posts. Slide the tile back and forth or use a rubber mallet to bed the tile into the adhesive or mortar while releasing air trapped underneath.
Spin the levelling cap on the spacer post and tighten to achieve a level surface across the joint. After the mortar is cured, unspin the caps and snap off spacers in the direction of the joint. Caps and anti-friction shields can be reused.