There 27 nakshatras in 360 degrees and 12 signs. The placement of Moon in a nakshatra determines the first letter of your name. Each nakshatra has 4 padas.
Chitra nakshatra has pe, po, ra, ree as first letter as per the pada. swati nakshatra ru, re, ree, ta.
In this way the first letter of the name is decided.
But many times, we do not find a suitable name with this letter of our liking and we name the child according to our own choice, but as per the birth chart the first letter is decided by the Moon's placement in a nakshatra.
As per your moon sign.... your name should start with "RA"... but its up to your parents what they wish to keep.