If I want to see an internal reference which has been placed on my personnel file, is the originator of the reference obliged to be told that I have asked to view it?
I think you're thinking about your Data Protection rights, rather than FOI. FOI applies to public bodies only, and is generally not about personal information. I don't believe that there is anything in data protection legislation that would mean that the originator of the reference would be informed. However, there may be an internal policy that would require the originator to be informed.