I think instead of F---
Pentax should show the page number in the manual that explains this.
Or the rear screen gives a message like:
"it appears this is the first time you have used a fine vintage pentax lens, please read pages xxx-xxx of the manual. Click here to not show this message again."
Not to flame the OP, but this has got to be the number one question posted by people that have a new pentax and an old lens. You would think Pentax could make it a little easier to understand what is happening.
By the way, the "clunk" you feel in your camera when you shift it from side to side, is the SR mechanism.
I think that answers the second most popular question.
Be aware of old Ricoh lenses. They get stuck on autofocus Pentax bodies.
Welcome to the forum, Hope you enjoy your new gear!