Hi Dan. Yours is a good question from which to recap these controls. I'll augment Ian's response.
While F is a simple concept in a biomass dynamics model with a single fishing fleet, the concept of "F" as a single number is very incomplete when there are multiple fleets, some with length-based and/or dome-shaped selectivity. In SS, the F multiplier is multiplied first by fleet-specific relative F's to get the F for each fleet, then that fleet-specific F is multiplied by the age-selectivity to get F at age. Depending on the choice of selectivity pattern, these age-specific F's may or nay not peak at 1.0 and can even exceed 1.0 in some circumstances. The realized F-at-age for each fleet is (F multiplier) * (relative F) * (age-selectivity). In addition to what Ian described, you can see the results under Exploitation in report.sso.
While F multiplier is always done as just described, the user has various options for the reporting of the realized F. These are in starter.ss and described in the manual.