Soften the Edge of Transform Tool in Fusion

There is a SOFTNESS option in cropping section but how can I have the same effect in Fusion for TRANSFORM TOOL? I want to soften the edge of my picture in a Transform Tool in Fusion.
https://forum.blackmagicdesign.com/
https://forum.blackmagicdesign.com/viewtopic.php?f=21&t=139770
Roen Davis wrote:Add a mask node.
The softness has to eat into the footage.
I hope it makes sense.