Sometimes it is harder to find people after 1900 especially when census only go to 1911 The USA is up to 1930.
I looked at the 1911 Census for Fermangh, which is the rootsweb message board you are on.
There are a number of persons on the 1911 Census but not in Fermanagh.
Samuel Risk age 50 (abt 1861) living as a boarder in the home of Charles Milligan, everyone Church of Ireland and born in what was known as Londonderry.
Samuel was listed as a painter and widowed, son Thomas 12, school and daughter Marget age 17 a factory worker.
The only Margaret was married to James Risk living on Cheviot Ave. Part of Victoria Co. Down. Married 10 years, born Scotland. James born Scotland, Presbyterian, an Engine Fitter, son James born Co. Down
These and 51 other Risk's listed in the 1911 Census of Ireland. www.nationalarchives.ie
Any births, marriages and deaths after 1864 can be accessed at the General Registry Office for either Northern Ireland or the Republic of Ireland. I only know the Dublin office does a 5 year search around a year, so exact dates are helpful but not always important. www.familysearch.org
is under maintenance at the moment but check there and also the PILOT program whose records go up to 1950's in Ireland. There were lots of US records for this name.
There was a Samuel Gibson Risk born in 1818 Co. Antrim and
a Samuel Risk born in 1827 Co. Down.
'genealogy for fun'
9 births for Margaret McClelland between 1849-1856 in records that only go to 1904. 3 in 1851 in Antrim as well as others in Donegal, Lough, Antrim, Down.
1 death for Margaret Risk 1870.
I usually advise people look to two websites with generic information for searching Counties of Ireland:www.censusfinder.com
United Kingdom+Ireland+Co. (Derry)*www.igp-web.com
*In Co. Derry in the 1600-1900 Freeholders & Voters List is a Samuel Risk.
There are no Risk families listed in the www.eircomphonebook.ie
for Derry or Fermanagh, I didn't check each County.