How do I soften single-layer water shoreline?

[motorsep]

@sarahlenker

If you plug it into the Alpha of a lerp for your opacity, this will have the effect of creating a natural, smooth fade in around any meshes that are near to the water’s surface.

Sadly, it doesn’t seem to work:

If I swap opacity values, I get this:

P.S. I don’t know if it makes any difference, but I am in forward DX12 in 5.5.4