real time CGT submission

I am trying to complete an online real time CGT submission. Where/ how do I report proceeds of a non uk property sale with CGT already paid in the appropriate country with whom we have a reciprocal tax agreement?

Hi carrick,
Please see the guidance on selling overseas property here: 
Tax when you sell property
We are unable to provide specific advice tailored to individual circumstances however you may be able to claim relief if you are being taxed twice.
Thank you. 

Not a very helpful reply. I am not asking for specific information - the question is - where in the real time online submission is the provision for recording the CGT already paid in a country outside the UK? Shouldn't be a difficult question for an HMRC administrator.