I noticed you didn't state even one DOB, DOM, etc. This makes it tough. The only saving grace is that the name Ratigan is so rare.
I searched the Irish Family History Foundation's database. It contains 12,000,000 surviving rcds for abt 65% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800. Unless you KNOW the county of origin, the chance that your ancestors' rcds AREN'T in the database is AT LEAST 35%.
For Pat(rick) Ratigan B ???? in Summerhill parish, Co. Meath, with a father named Mat(thew), I found only 2 B rcds: 1846 and 1852. One of these MAY be for your ancestor.
Google the Foundation's name to lead you to this database. Register, opt to be notified as rcds are added and browse. Pls post your search results to my genforum msg.