There is only one file type that uses the .OLK14SIGNATURE extension:
Outlook Signature File
HTML signature saved by Microsoft Outlook for Mac, an email program that replaced Microsoft Entourage; contains an email signature that is formatted using HTML code; saved and loaded automatically through the Outlook interface and is not directly accessed by the user.
Microsoft Outlook for Mac saves OLK14SIGNATURE files to subdirectories of the following directory:
[user]/Documents/Microsoft User Data/Office 2011 Identities/Main Identity/Data Records/Signatures/
|Microsoft Outlook 365||Free+|
Updated: January 1, 2011