Richard Prentice found in:
Canadian Genealogy Index, 1600s-1900s
Place: Kingston Township
Province of record source: Ontario
County of record source: Frontenac
Source: Norman K. Crowder, Early Ontario Settlers, A Source Book, Genealogical Publishing Co. Inc., Baltimore, Maryland, 1993.
1784 Provisioning Lists:
Return of Disbanded Troops and Loyalists settled in Township No. 1 Cataraqui (Kingston); mustered this 9th October 1784
Richard Prentice, 1 man, 1 total, 1 rations per day, acres cleared: 1; on his land, back concession
From reading the list you mentioned, it seems that perhaps his actual service was not readily proven and so he was said to be a Loyalist by someone who was of some authority. Unfortunately, from the list of abbreviations, it does not give what A.McL. stands for, although it may be another Loyalist.