Neil,
Thank you so much for wanting source citations! As long as you are getting the basic information so that other's can find it, WikiTree doesn't have a set policy.
A general citation could be:
"Statutory Register for Births 334/16," database, ''Scotland's People'' ([putwebsitehere Statutory Register for Births] : accessed 2 January 2018), entry for Peter Dow, 8 Oct 1914, Blair Atholl Parish, County of Perth; citing Parish Records (or whatever it says the source is).