I was just in Edinburgh working with the Kirk Session records of Rerrick and you will have to use them at the West Registry House in Charlottes Square. Unfortunately this parish has not been digitalized so it isn't on the Virtual library on the Archives computer so you needn't go to the main Register House as they will refer you to the West House and it is best to order the book you need and have it sent to the West Register House. The number of the archive you need for Rerrick is CH2/ 311/11. But for the period you are wanting the book is for 1827-1870 and very easy to read, the pennmanship is very clear and I found it very interesting reading.
Eventually all of these session records will be digitalized and available on the Scotlands People site sometime in 2008 or 09. I am in the archive program at the U of Dundee and one my fellow classmates has worked on this project.
Hope this helps.
Jody Allen