The familysearch site has a record of the marriage of a Patrick O'Kane and Elizabeth McLaughlin in Limavady Co.Derry in 1914. The reference for the Central Records Office (http://www.groireland.ie/fees.htm) is
Name: Patrick O'Kane Registration District: Limavady Event Type: MARRIAGES Registration Quarter and Year: Oct - Dec 1914 Volume Number: 1 Page Number: 891
You can fax them for a photocopy if this is the correct record.
the ifhf site also has a record of a marriage of a Patrick and Elizabeth...Patrick's father's name is Thomas:Elizabeth's father's name Patrick
There are records of births to a Patrick and Elizabeth (McLaughlin) O'Kane 1915 Ellen 1916 Daniel