An 'authentication' can be provided by National Records of Scotland for a fee. Please email the General Register for Scotland authentication of extracts section by using their Contact Form. They will be glad to help and will advise you of the current fee.
Please note that an 'authentication' is not acceptable to every foreign government and some ask for what is called an 'apostille' to be written on the back of an extract. This procedure is governed by international convention and the Foreign and Commonwealth Office is responsible for adding the 'apostille'. If you require an 'apostille' please contact the Foreign and Commonwealth Office on 0370 000 2244.