My son is 9months old. he is thin. wt healthy foods shall i provide?

Review the velocity: Of all growth parameters (weight, length, weight-for-length & head circumference) & development with his pediatrician to determine if there's a need to evaluate for causes of under-nutrition. Allow him to finger-feed nutrient-dense foods & drink from an open-mouthed cup held by you at scheduled sit-down family meals & snacks. Limit formula to 32 oz./day. Avoid juice, sugary beverages & " grazing.".