particle: is the name of a particle to create. (See Spigot Particles).
xyz distance: specifies the dimensions (in number of blocks) for each dimension of the particle effect, with x y z in the center. Each coordinate specifies the number of blocks from the center that the particles will appear.
maxSpeed: is the speed of the particles.
count: is the number of particles to create.
In this example I am spawning 10 particles in the same place.
After that you can move the particle wherever you want.
I will leave it in front of the head
And that's it, it's spawned in the right place, you can move the particle and change it if you wish.
This is an example:
In BlockBench
In Game
Note: Before editing an existing keyframe particle you must reset it to avoid any problems.