Use the Keyer RGB to extract a key by adjusting tolerance and softness using red, green, and blue ranges.
To access the Keyer RGB menu, use:
Batch, then select a node from the Node bin.
Timeline, then use Batch FX (see Creating Batch FX).
The Modular Keyer, then select a node from the Node bin.
This node accepts a front clip, and outputs a result.