They are designed to be used with particle systems, what is your use case?
This is the option used in the demo, for sprite sheets, you need to enable animation (by adding a CanvasItemMaterial with the "particles_animation" property checked and the animation parameters configured, you should be able to find tutorials on this if you aren't familiar with it).
I could release a pre-configured example project, but in the meantime, I hope this helps.