Kenneth Macdonald was farmer at Scarista, and according to this article by Direcleit, had relinquished the factorship over South Harris by 1883. The fact that Kenneth was born in Applecross helped me to trace him on the census records. Kenneth Macdonald's wife is named as Mary Macrae by Direcleit, but the 1881 census record names her as Jane. The census transcript on Ancestry quotes Kenneth's occupation as "Farmer & Factor No Of Acres Unknown Employing".
In 1881, we find Kenneth, aged 64, with his much younger wife Jane, aged 36, at Big Borve. They have 3 three children, Emilie P S (4), Alexander (2) and John (9 months). Kenneth's sister Catherine (50) is there, together with a handful of farm- and house servants: John Mckinnon, William Campbell, Marion Mckinnon, Marion MacCuspaiz [Maccusbic?] and Mary Mckinnon. A decade earlier, Kenneth is shown in the company of Rebecca Macrae, his sister-in-law, but his wife Margaret [edited] does not appear on any of the census returns. He is only apparent in Harris from 1861 onwards. Kenneth's last mention on the census for South Harris is in 1891, when he is shown as a farmer at Hamlets Scaristavore, with his wife Jane and sons Alister (= Alexander), aged 12, Jan (John) aged 11 and Kenneth (9).
In 1871, Kenneth is listed with his sister-in-law Rebecca Macrae as a farmer in Harris. In 1861, the census records him as a sheepfarmer employing six labourers at Big Borve, with 4 of his servants in the house.
On 22 May 1891, only a few weeks after the census was taken, Kenneth passed away after suffering from broncho-pneumonia for six days. He was aged 80. His parents are mentioned as John Macdonald, a tailor, and Isabella Macdonald MS Macleod. His death was registered by his widow, Jane Margaret Macaulay Mackenzie.
EDIT: Added information from 1871 and 1861 censuses, and this link to his evidence at Tarbert.