How to Create Chroma Key transitions.
Transition IMAGE A > IMAGE B
Download the CK file you want to apply.
Insert IMAGE A in the timeline.
Overlay CK file over the end of IMAGE A.
Apply Keyer effect to the CK file and select Green color.
Merge the videos to create just one.
Insert IMAGE B under the end of created video.
Apply Keyer effect to created video and select Blue color.
Go to Chroma Key Transitions