I can't see him at all in the R.I.C., but this looks like him during WWI.
William Cormack Burnett born 12 August 1899 at Machar, Aberdeen. His father was Robert Burnett of 15 Allan Street, Aberdeen. William was a ship-wright by trade.
4th April 1921: Discharged. Sapper with No. 1 Field Company Royal Engineers (Highland Division) Defence Force.
14th April 1921: Recalled for 90 days emergency service to 51st Highland Division, Royal Engineers Defence Corps.
4th July 1921 Discharged.
William was 5ft 2ins in height, a fresh complexion with dark hair and blue eyes.
Added: He also had a tattoo on his forearm of a hand clutching a heart
Do you have his Army records from WWI? There are loads of them from 1917 onwards, although many are repeated.