How it counter earth rotational velocity when trying to go into a specific inclination?

@sflanker ok

The way I do it is take the East vector and rotate it by my desired inclination CCW around my position vector (which is "Up" relative to the surface of the planet), and then I multiply that by my calculated orbital velocity. This craft has custom expressions for doing vector rotations (as well as a ton of other stuff).

@sflanker how would I convert my target inclination to a PCI vector

you can set velocity to orbital so just counter it that way

@sflanker okay

This is slightly imperfect, but you can take your desired orbital velocity vector, subtract from that your velocity vector due to the rotation of the planet while you are sitting on the surface, and then find the angle between that vector and the north vector to determine the launch trajectory. The reason this is imperfect is that your change in velocity is not instantaneous. As a result I believe you will continue to pick up excess lateral velocity during launch. I'm not sure how this is simulated in SR2 but in real life I imagine that a rocket has lateral force imparted on it by the fact that the atmosphere is rotating with the planet. To get a perfect inclination you will probably need to continually check your current velocity vector (or orbital inclination) against your desired vector or inclination and adjust your heading to compensate throughout your main engine burn.