If you're concerned about the size of the food, take a pellet and use your fingernail to cut it in half. (It might crumble when you do this, but that's OK.) You can feed him smaller pieces this way.
Top Fin is an OK food, but it has a lot of grains (soybean, wheat, corn, etc), which can cause constipation in some bettas.
On this forum, the two most often recommended foods are New Life Spectrum (NLS) betta pellets and Omega One Betta Buffet pellets. (Petco carries both brands. Petsmart has Omega One.)
Chandler sounds like a good name.