In the 1803 agricultural census there were 8 Kerr households in Cluntyfinnan (surname spelled Carr then). The census only lists heads of household so it’s not possible to glean who else lived in each property. There were 2 Johns in the townland. You can see the census on Bill McAfee’s site, under “databases from 19th century substitutes.”
https://billmacafee.com
3 Carrs in Loughguile parish in the 1740 Protestant census (also on Bill McAfee’s site). Townlands not listed in that census.
There were 5 Kerr farms in Cluntyfinnan in the 1832 tithes:
http://www.irishgenealogyhub.com/antrim/tithe-applotments/loughguile-parish.php
In Griffiths Valuation in 1862 there were also 5 Kerr farms, all in Cluntyfinnan West:
John plot 10
James plot 11
Samuel plot 12
John jr plot 15
Thomas plot 16.
Today those farms are straddled along the modern Clontyfinnan Rd. (Roadnames were only introduced in the 1950s).
By the 1901 census there were 2 Kerr households in Cluntyfinnan West. 2 were Presbyterian and the third Reformed Presbyterian:
http://www.census.nationalarchives.ie/pages/1901/Antrim/Ballycregagh/Clontyfinian_West/
By 1911 there were 2 Kerr households:
http://www.census.nationalarchives.ie/pages/1911/Antrim/Ballycregagh/Clontyfinnan_West/
The Reformed Presbyterians may have attended either Kilraghts or Derviock RP church, they are the 2 closest. The Presbyterians probably attended Bushvale Presbyterian church. There’s a Rev Thomas Caldwell who was executor of a Kerr will in 1902 so possibly he was the family Minister. He was Minister of Bushvale (sometimes called 2nd Kilraghts) from 1879 till 1932. None of these churches has any records for the period you need (ie late 1700s/early 1800s) and so tracing John & Ann may be challenging.
There are several Cluntyfinnan Kerr gravestones in Bushvale Presbyterian graveyard. They have been transcribed and can be found on the Causeway Coast & Glens FHS website. (You need to join to access the records).
There is a local Facebook page for the Armoy area. You could try posting on it in case any Kerrs still live in the area.
https://m.facebook.com/armoycommunityassociation/posts/6045428932154821/
PRONI names search site records that a will for Robert Kerr of Cluntyfinan was probated in 1849 (so he died around that time). The will itself was destroyed in the 1922 fire and no other information has survived.
Found these probate abstracts on the PRONI wills site:
Letters of Administration of the personal estate of Thomas Kerr late of Clontyfinnan County Antrim Farmer who died 22 January 1895 were granted at Belfast to James Kerr of Clontyfinnan Farmer the Son.
Probate of the Will of Hugh Kerr late of Cluntyfinnan County Antrim Farmer who died 5 June 1902 granted at Belfast to The Reverend Thomas Caldwell Presbyterian Clergyman and Robert Kerr Farmer.
The above will is on-line on the PRONI wills site.
Kerr James of Clontyfinnan West county Antrim farmer died 23 December 1933 Administration Belfast 10 December to Thomas Kerr farmer. Effects £110 10s.