@edb
I've tried a few different ones that work quite nicely; unfortunately they generally only work with Unity sprites or 3D meshes.
If you ever happen to find an easier or plug-and-play shader method to generate a nice outline or glow around *animated* 2DTK sprites, please let me know.
From what I've read there's a few methods, but none that don't require a pretty significant amount of work, as far as I can tell.
It would be fantastic if 2DTK could use the Sprite Renderer as an alternative to the 2DTK Renderer, but I believe Unity hasn't exposed enough for him to integrate them (or at least, as of mid-2017, perhaps that's changed now!?). It would be ideal though, because then we could use a lot of the bells and whistles that Sprite Renderers enjoy while keeping stuff like 2DTK's much superior animation workflow and other features.