Kramer VM-1021N User Manual page 12

Note:

Terminate unused inputs to 75Ω, and terminate active inputs at the
connecting source

The output signal format must match the input signal format (for example, if
the input is composite, the output is composite)

All signal cables to each device should be of equal length (for example, the
R,G,B cables between a camera and the amplifier should be of equal length)
VM-1021N - Connecting the VM-1021N 9