https://www.offside.hk/league/premier-league-aims-for-mid-august-start-raises-foreign-quota/ Premier league clubs will be allowed to register an unlimited number of foreigners, name 6 on matchday and use up to 5 at a time
Olexiy Shlyakotin and Stefan Antonić is playing for sham shui po. Also, Olexiy Shlyakotin can play for Hong Kong national team in 2023 July.
https://www.transfermarkt.com/sham-shui-po/transferrekorde/verein/34332/saison_id/2022
https://news.mingpao.com/pns/體育/article/20220514/s00015/1652465660702/居港將7年申入籍-冀助港超隊戰亞洲賽
It should be at most 6 foreign players in the match squad and maximum of 5 can be starting 11. Also, squad registration don't restrict the number of foreign players registrated.