I had Vacation to Cuba (cayo cayo ) with Airtransat last month, we have RTD without PR Card and everything was great. no issue at all. there is some point maybe you need to know
1-When back to Canada we could not use Custom`s Kiosk because it won't scan out passport and we go to the officer and he filed custom paper for us
2- in the airplane, before arriving in Cuba they gave you a "Tourist Card" and you need to write your Nationality, do not worry its not a problem at all.
3-when back to Canada officer just ask for our trip duration and after 5-8 min they put arrival stamp our RTD, they do not ask for Decision paper or Work permit or anything, but i suggest keep them with you just in case