According to the 1901 census, John was born in Kirkcudbright around 1889 (he was 12 in 1901)
Ploughman, John married Mabel Kennan in Twynholm in 1911 and they had at least seven children.
In the scotlandspeople indexes, I have found the death of a John McSkimming aged 78 in 1967 in Kirkcudbright. I guess that this death may be this John.