How can I calculate the right ascension of an observer on Earth's surface in the TEME frame with python.skyfield? I would like to calculate the right ascension of a point on earth as specified above with the Skyfield Python library, and I can not figure out how to do this.
I know that calculating the geocentric position of the respective Topos object at a specific time  results in a Geocentric object that has an attribute .radec; however I am not confident that this delivers the right ascension in the TEME (Earth centered inertial frame.
An Earth-centered observer looking at that point on Earth’s surface would also be looking toward the point that is the zenith for that location on Earth.
Thus, you just need to find the local sidereal time (LST) for that Earth location.  That gives you the right ascension on the meridian for that place and time.  The meridian passes through the zenith, so that would give the R.A. of the desired point.
It looks like Skyfield has a GMST (Greenwich Mean Sidereal Time) attribute for any time object you create.  To go from that to LST, convert your longitude to hours (15 degrees per hour) and subtract if it’s west, add if it’s east.
So something like this:

from skyfield.api import load
ts = load.timescale()     # Timescale object
t = ts.now()   # Time object

RA_hours = t.gmst - west_longitude_degrees/15.

where you could change to a different time if you want, and you’d have to define that longitude variable.
You’d also want to check for negative values and make sure your answer falls into the 0-24 range, adding 24 if needed.