Well, to my knowledge, Kohaku NEVER kills Rin. He tried, but Sesshomaru stops him before he does. I believe this happens in episode 81. The same episode has Kagome meeting Rin. Well, sorta. They meet, but they never really interact with each other.
If you want to see Kagome and Rin actaully talk with each other and REALLY interact, then see the 3rd Inuyasha movie. Lots of Kagome and Rin together in that movie.