Your reference letters should cover the following:
1) How long have you known the applicant?
2) In what capacity do you know the applicant? (e.g. professional, educational, supervisory, voluntary, religious)
3) When you last had regular contact with the applicant
4) A brief overall endorsement of the applicant, including their:
Skills in leadership and networking
Personal, intellectual, and interpersonal qualities
Ability to complete a demanding academic program in Canada