Joe Lee, it's nice to see your first question on this web site !
Someone may have told you that your Classic Cobra 29 pushes out 60 W, but i believe some wishful thinking or just plain exaggeration was involved there, this radio is only capable of 5 - 10 W max.
Then, despite what may seem, in reality the difference in getting out between 10 W and 15 W will be hardly noticeable. If you increase the power of a CB from 10 to 15 W, at the other end the person listening to you will only notice a tiny amount of improvement.
To answer your question, the S/RF meter in your CB radio has two functions, it shows the received signal strength of stations or people you can hear when you are listening, and then it shows the output power of the CB when you are talking or transmitting.
When you are listening or receiving, the meter reads the signal strength of the people you can hear, this is the "S" part of the S/RF meter.
Then, when you are talking or transmitting, the S/RF meter will read the output power of your CB, this is the "RF" part of the S/RF meter. It should normally go up to about 2/3 of the way when you are talking.
You just have to make sure that the left most 3 position switch on the front of the radio is set to S/RF. The other settings for that switch are for checking if the antenna is tuned correctly, i would just leave that for now. This switch has no effect on how you get out, regardless of what it's set to, it only affects what the meter is showing.
When listening or receiving, it is normal for the meter to go from zero all the way to the end, or anywhere in between, depending on how strong the people or signals are that you are listening to.
Hope that all makes some sense !