Hi,
As UK resident you are required to report your worldwide income to the UK.
You should check the Statutory Residence Test here RDR3 Statutory Residence Test as HMRC are unable to confirm whether or not you are eligible for split year treatment.
RDR3 Statutory Residence Test
Please also see Tax on foreign income: Overview.
Tax on foreign income
As SA109 is not supported by HMRC software you will need to purchase commercial software if you wish to submit your return online.
You will find a list of commercial software suppliers here Self Assessment commercial software suppliers.
Commercial software suppliers for Self Assessment
If you do not wish to purchase commercial software then the form will require to be submitted by paper by 31 October. Based on the information you have provided, you will require to complete SA100, SA103, and SA109. SA106 will only be required if you wish to claim Foreign Tax Credit Relief for any tax deducted on this income in Hong Kong.
Thank you.