I have a png with an alpha layer, looking around, I see no options for using the alpha layer, how do I do it?
hmmm, I’m not seeing what I’m supposed to do, I set it to true color, and nothing changed, to 16 bit nothing changed, when I made the max size 2048, still nothing, I don’t really see where it explains alpha layers in per-platform overrides.
You can use it right out of the box if you did not use Photoshop for creating your png 
I prefer using GIMP for creating Textures with alpha.
If your question is “how do I make a texture display with transparency ?”, you have to use a material with a shader enabling transparency. The engine won’t display the alpha channel juste because it is present in your texture, you have to explicitely choose a shader that will. Those shaders are all in the “Transparent” folder of the material drop down selection.
I’m having the same problem. I downloaded Filter Forge and I’m trying to get the alpha maps to work. If I put a black background under the image then I can get it to alpha ok but I don’t want the metal grate to be alpha at all. This is what I am trying to work with:
I want all of these to be on one texture so I have a nice and shiny fully visible grate with a normal map but I can’t find where I can insert a seperate alpha map from the image.
No one knows how to insert an alpha map into a shader?
We use Photoshop, which sucks, but it will do the job properly if you save as a TIFF file.
it also does the job properly if you use SuperPNG exporter.
Photoshops own PNG exporter was trash since Photoshop 6 and thats also the time since SuperPNG exists 
We tried SuperPNG and found it produced similar results to the built-in PNG export. Or do you mean respecting explicit alpha channels so that you can define the RGB values even when A = 0? I’ve been using BigPNG, although to be honest I haven’t checked whether it supports explicit alpha channels.
I just checked, and BigPNG does not support explicit alpha channels.
When I try saving as a TIFF file, it says it has to merge the layers together. Does that matter? I tried having the picture with the alpha layer under it.
I meant it in relation to sending through all color informations independent of alpha presence etc yes (-> usage of png in game dev)
With Unity there is generally one thing to keep in mind / fight when it comes to PNG (or also PSD): Unity unhappily does not expose a simple option to make it ignore the color profile persent in the png, so stuff can backfire if the wrong profile was used.
And as SuperPNG is meant for reasonable usage, it contains these profiles.
What wer the explicit problems you had?