The regular kara palm method requires a ST LK .Like this:
1. qcb, st.LK~any punch (LP/MP/HP)
or
2. qcb, st.LK~any two punches pressed simultaneously (LP+MP/MP+HP/LP+HP)
If you cancel st.LK to a punch fast enough, Yun adds range to the Palm Strike which moves forward a bit. Thus, it is possible to connect a Palm after any F+MK in corner genei-jin combos.
However, there is another method which works on
-Shotos (Ryu/Ken/Sean/Akuma), Urien, Makoto and Twelve (medium hit box)
-Hugo, Chun-Li, Elena, Q ,Alex (big hit box)
New Kara Palm method by toastedguy:
qcb,F(Just tap the forward direction fast enough), st HP
You can pull off the corner genei-jin combo xxGJ,st MP, Dakai, {F+MK, Kara Palm}x3, Ender of your choice without that st.LK Kara on the chars mentioned above!
Advantages:
-Easy to master.
-3 Kara Palm genei-jin combos are no longer risky. If your timing is off, Dakai comes out instead of a palm, but you do not drop the whole combo. A dropped LK Kara Palm input does not add range, so you miss the whole combo.
Disadvanteges:
-Does not connect on others characters consistently. Dudley, Remy, Ibuki, Oro and twins have a smaller hit box.
Credit goes to toastedguy.