RCA is really just a brand.  Googling your model number also turns up Provision and Curtis models, so I suppose that this TV is really a Taiwan design.  It may use the NEC1 IR protocol instead of RCA.  The issue then becomes finding which IR protocol the TV responds to.

Frankly, this is likely to be a frustraing task if you just try various setup codes.  There is no assurance that the Atlas will have the matching device number.  If the IR protocol and device number(s) were known, then it is easy to program the Atlas via a JP1.3 flash cable (about $20, plus 20 minutes to swap the pins from a 1X6 connector to a 2X3 connector).  Some Atlas remotes are learners.  Try the 975 command to see if it blinks twice. 

If you do wish to get a cheap learning remote, I would buy the RCA RCRP05B.  It has every button that the Atlas has, and like the Atlas, is made by UEI and was designed as a cable company remote. It is <$20 at Amazon, etc. (The RMVLZ620 is actually also made by UEI, but it isn't adaptable in the way the RCRP05B is.)  

If you get both a JP1.3 cable and the RCRP05B, then you can decode the OEM remote, and program the Atlas, if you like its form factor better.