Dietitians Act Article 43

Special municipality and county (city) dietitian associations shall be organized by more than 9 dietitians practicing within the administrative region. In areas with less than 9 practicing dietitians, dietitians may join the association in a neighboring area or organize a joint association with dietitians in a neighboring area.
中文原文 營養師法第43條
直轄市、縣(市)營養師公會之設立,由在該管區域內執業營養師九人以上發起組織之;其不滿九人者,得加入鄰近區域之公會或共同組織之。

English translation for reference only; the Chinese text prevails. Not legal advice.