Your Skill Bonus is a modifier added to any stat roll made when using the Skill attribute type to perform a task (see Types of Attributes). At level 1, a character’s Skill Bonus starts at 3. This number will increase by 1 for each even numbered level you attain thereafter. At level 2 it will become a 4. At level 4 it will become a 5, and so on.
Using your Skill Bonus
Player: “I want to fire a grappling arrow with my bow and try to hook the rooftop of that distant building. I have my Bow Master Skill that uses my PA stat.”
GM: Okay. Your PA is a D12, and at level 1 your Skill Bonus is a 3. Go ahead and roll a D20 plus a D12, then add your Skill Bonus modifier to the result. We’ll see if your grappling hook catches hold.”