With that mixture ratio between potassium borohydride and sodium hydroxide, I can't see why the difference between sodium and potassium could be significant. Molar weight is different, so be sure to make your conversion properly - and maybe substitute a pinch of KOH for a pinch of the NaOH just in case.

I checked: You'll need 0.14 gram NaBH4 to replace the 0.2 gram KBH4.