Prior Service:
Step one: Using a complex mathematical formula based on wage increases, inflate all your prior earnings to current year earnings.
Step two: For each calendar year of inflated earnings, calculate the contributions for the part-time pension plan using the current contribution rate. Those rates have increased by 0.3% each year for the past two years; you snooze, you pay more.
Step three: Add 7% compound interest to each year above. Add them together for all your years of service.
Voila. Your contributions to the Reserve Pension Plan.
If you are moved into the full-time plan,
Step four: For each year's inflated earnings, calculate what your contributions would have been if you had earned that much and were a contributor to the Regular Force plan (based on current year contribution rates and YMPE). If your Reserve contributions calculated in step two (above) are more, no change. If they are less, pay the delta between the Regular Force and the Reserve Force plan.
Step five: Add together your Step 3 and Step 4 contributions.
Voila! Your contributions to the Reg F pension plan.
There are additional considerations. You are now getting employer contributions to your pension. These reduce RRSP contribution room, and what's called a "Past Service Pension Adjustment" is necessary - if you lack sufficient unused RRSP contribution room, you may have to withdraw money from RRSPs and have it taxed in your hands to allow you to buy back your full service. The CF Pension office will send your file to CRA for confirmation; if you don't have enough contribution room, CRA will send you a letter telling you how much you need to withdraw.
In my case, for example, I transferred about $60K from my RRSPs to the pension plan (payments and interest). I had about $22K in unused contribution room for RRSPs. However, the employer contributions for my prior service are worth roughly $45K. For adjustments like this, you are allowed an $8K over-contribution (which will be reduced over time). So: $45K employer contribution - $22K contribution room - $8K over-contribution = $15K too much in RRSPs - I had to withdraw $15K from RRSPs which will be taxed in my hands this year.
Oh, and from the day the CRA sends you the PSPA notification to the day you return it in the mail, with the RRSPs withdrawn is a maximum of 30 days - so get ready to act quickly. (You can request extra time if you need to).