I have 6 neon tetras with my bettas. The male chases them sometimes but it is impossible
for him to catch them. I think tetras are good tank mates for a betta because they stay low and the betta stays near the surface.
When I feed my betta I crush some flakes with his food so they fall down for tetras to eat. They will eat everything that is falling down if you crush it nicely and don't put too much.
I have an 8gal tank with male and female divided with a piece of wood and a safe net through which tetras can go through. They prefer to stay with the male even though he chases them occasionally.
Just wanted to share my experience. :)
P.S. This is my reply, that I copied of another thread, since it regards the same question. Hope you won't mind.