Melee Finisher modifier stacking, for my reference.
Base * (1 + WeaponMult) * (1 + Finishing Touch + Covert Lethality + Fatal Teleport*AbilityStrength) * (1 + Radiant Finish*AbilityStrength) * (1 + Savage Silence*AbilityStrength)†
...where mods correspond to their "Additional Damage" value (e.g. maxed Finishing Touch yields +0.6)
† Note that the modified ablitity tooltip for augmented Silence reflects the final multiplier for Savage Silence (1 + XX%*str), while the mod description lists the additional damage before ability strength (+XX%). This is NOT the case for Fatal Teleport or Radiant Finish, where both mod and ability tooltips list additional damage (with the ability tooltip including ability strength).