Bah, no one says "TK2D" until after I post lol.
Make sure you have TK2D Premultiply Alpha checked
And you can use the Spine Skeleton shader. The TK2D shaders don't use the same methods as the Spine editor so if the goal is to keep everything looking the same, you should use the provided shaders 🙂
I just updated the TK2D runtimes to be more in-line with the Spine-Unity ones.
They're available here and on Git.
http://www.esotericsoftware.com/files/r ... itypackage
There are a couple bugs, make sure when you create a SkeletonDataAsset that you assign the tk2dSpriteCollectionData before the JSON or it will have a bad day.