add value to shipping service
You are editing the component rule for the flat rate. Instead, you'll want to create a shipping pricing rule.

http://youtu.be/trLydGpimD4?t=10m7s

In that video, I show you how to set up a shipping pricing rule that only runs on a particular flat rate service ... I've linked for you to jump to the part of the video that walks you through that.

The two conditions you're looking to add:

Entity has field (it should have the shipping service field)
Data Comparison (the shipping service field should equal whatever flat rate you want to tweak)

Josh