To get you on the right track, 1.Nf3 d5 2.c4 is a Reti (ECO A09/01 or
NIC QP.09.2) not a KIA. About 4 replies are generally acceptable
though others have been tried. 2...dxc4 is a Reti Accepted where it
looks like a gambit but White has little problem recovering the pawn.
2...e6 can be played to support the forward pawn but has the
disadvantage of blocking in the white-squared Bishop. 2...c6 is also
played to support the pawn and the downside there is taking away
what might be the best square for a knight. However, both 2...e6 and
2...c6 are considered very solid replies setting up a pawn phalanx in
the center which White has to prove he can break. Lastly, 2...d4 is a
Reti Advanced and is considered somewhat enterprising where Black
will try to cramp White's position and make development difficult. His
challenge here is to fortify and hold this center and keep the thumb
on White. White's challenge is to develop and find the right moment
to break the d4 pawn (or go around it). Choice of how to go is a
matter of taste. The first tends to be wide open and can be easily
driven completely by tactics, the middle two tend to be positional in
the opening and highly transpositional and the last tends to be
positional until the middlegame and then explosive if the right pawn
break occurs.
-ww-