Reserves can be determined by adding up all the cost and schedule reserves in all these planning processes.
When Performing Quantitative Risk Analysis, you are analyzing the effect of each identified risk on your overall project performance. For example, if one of the identified risk is that one of your key engineer resign in the middle of the project, your risk response is you need x number of days to hire one with a budget of $x. The number of days and cost will then be added to your schedule and cost baseline.