Hi,
This doesn’t work. The multiplied look is lost the moment you remove the base layer. The best solution I found (but not perfect) is to put the base layer above the “top” layer and multiply the base layer over the “top” layer. Then, you make the base layer a clipping mask by pressing cmd+alt+g. Then, flatten the image and it is a normal blend layer, with the multiplied look, with transparency. It does have some artifacts in Nuke though. PNG is a compressed format and Targa is only 8 bit. I wish 16 bit tiffs worked well in Nuke, but they don’t. The Foundry told me they’re working on it.