Adds a size change at a certain point in a particle's life. Scale values are relative to the value set by SetParticlesSize so a scale of 2 means double its normal size and 0.5 is half its normal size. A scale added with time=1 will make the particle equal the given size when it has been alive for 1 second. The particle will gradually transform from its current size to the next size.
AddParticlesScaleKeyFrame( ID, time, scale )