VTF Opacity/Alpha Channel Question

Rizz

L5: Dapper Member
Dec 18, 2009
210
21
I'm having a bit of trouble with a vtf material and I can't seem to figure out how to get my vtf to have an opacity applied to it.
I've googled the issue, and even watched an outdated video but to no avail.
Can anyone turn the following image into a vtf with an alpha channel/opacity map applied so I can see what you did?
glassd.png