With regard to: We are puzzled as to how it happened. (preposition)
According to: candidates who were chosen as to ability. (preposition)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "as to" in a sentence
"You know, they took a pool on the da Vinci as to what name you and Rinic would pick for my great-granddaughter."
"A very private club with cinder-block, barbed-wire-topped walls; with guarded, padlocked gates; and a membership exam so exquisitely obtuse as to be incomprehensible and unconquerable."
"Her name is Natalia Demkina, and scientists remain baffled as to why she can see through walls."