Hi ricksareen,
If you are resident in the UK you are required to declare your worldwide income in your Self Assessment tax return.
Your foreign gain should be declared on SA108.
If foreign tax has already been paid on your gain then you should also complete SA106 to claim your foreign tax credit relief.
Please see page 6 of
SA106 at question 33 onwards – Capital Gains – Foreign Tax Credit Relief and Special Withholding Tax.
Thank you.