Self employed income in foreign currency

I am self employed and earned Hong Kong dollars from conducting online tutorial lessons. When tailoring my tax return online, are the earnings under my "self-employed business" or should I consider them as foreign income and tick the box for "If you received any foreign income, do you need to complete the foreign section?"? Also, when I convert the earnings to GBP, what rate should I use? Thank you in advance.

Hi Kit Ming Sin,
If you have paid tax in Hong Kong on this income you will declare it as both in order to claim Foreign Tax Credit Relief.
If no foreign tax paid, it is under self employment.
The income must be converted to sterling using any of the rates ahere:
Exchange rates from HMRC in CSV and XML format
Thank you.