jtt96 here are some variations that can come out of the classical reti opening, for a little deeper information it would be best to check out Jrobi's channel on youtube where here explains a little bit more but to get a true understanding of the reti and it's power you have start useing it and study each move that black may do, as for DrSpudnik, although changing your opening move from e4 to Nf3 black may still open with the sicillian where it's recommeded to transpose in to the Kinkg's indian, or try to get into the yugoslav depending on the veriation of the sicilian.