Unless your betta is an absolute pig like my betta boy used to be, you should be fine just dropping food into the community. However, if he is, I found it easier to feed my betta in one corner of the tank and drop in the tropical fish pellets in the opposite corner for the harlequins whie he's busy. By the time my betta would finish his meal and get over to the other side, the harlequins would be done.
Unfortunately he is a pig he woofs down his 3 or 4 pellets and patrols the surface for a few moments afterward looking for more. I thought about using a breeding net to feed him in. That way I could assure he is getting the proper food and amount.