Any matching RRSP or TFSA employer contributions are considered a taxable benefit and must be reported on your annual T4s. If you’re not offering any matching contributions, then you won’t have any tax reporting responsibilities.
Employer contributions made to a DPSP on behalf of an employee must be reported as a Pension Adjustment (PA) on their T4 slips; this amount goes in Box 52.
A PA will reduce the employee’s RRSP contribution room in the following tax year.