It is the name of an Indian girl. It means the best of everything. There isn't a hurdle or challenge that can stop her. She is unconquerable, fearless and triumphant in everything she does.
Is a girl that you are lucky to meet. And should keep in contact with until you die. You should be nice to her because she is basically an angel on earth, so if you like a Rishitha you are lucky, but if she likes you back, then you are even more lucky.