HONG KONG, July 5 (Reuters) - Shares of Vitasoy were set to drop 11.2% on Monday after a worker sent around a memo offering condolences to the family of a colleague who stabbed a Hong Kong policeman, triggering online calls in China for a boycott of the company. In a statement on the Chinese social media platform Weibo on Saturday, Vitasoy said a staff member had circulated a memo that it described as “extremely inappropriate” without authorisation, and the company reserved the right to take legal action. Shares of Vitasoy were set to open down 11.2% at HK$26.1. (Reporting By Donny Kwok; Editing by Himani Sarkar)