Hello, I made this account today to try and get this question answered. We are Rogue Trader first timers, and we are confused as to what the "Characteristic Bonus" is used for. We can't fidn a single example of it being used in a skill check or characteristic test. All the tests appear to simply roll against the parent characteristic and any relevant difficulty modifiers. When do Characteristic Bonuses come into play, and can anyone give me a page in the rulebook where it says something explicit about them being used?

Strength and Toughness Bonus are used together for calculating your carry weights. Strength Bonus is added to damage for most melee weapons. Toughness Bonus reduces damage taken. Agility Bonus is added to your Initiative roll and determines how far you can move in a round. Intelligence Bonus determines how much you're able to heal someone, and can be used for Initiative if someone in the group gets Combat Formation. Perception Bonus can be used for Initiative if you have Combat Sense. Your Fellowship Bonus affects how many people can be affected by Charm, Deceive, Intimidate and other social tests. Some talents use your Willpower Bonus to determine range of effects, such as Blessed Radiance.

In addition to what Errant said, Intelligence Bonus is used to calculate how much can a character heal others using First Aid with the Medicae Skill.