He was educated at Fettes which he left at 16.
There is a music book at Melyniog titled 'Music composed by the late A R Reid - Kilmardinny'.
In the 1881 census, he is aged 20 and living with his family at Kilmardinny House, and has an occupation as a Clerk.
He went to Florida to grow oranges. He probably lived at Rose Hill Plantation in Leon County, Florida just North Of Tallahasse, which his father had purchased in 1892 but Alexander died the same year on the 10th June 1892 at Tallahasse aged 31.
References:
http://en.wikipedia.org/wiki/Rose_Hill_Plantation Reid Saga by Linnhe Reid.