The preference of voters shall be indicated by inserting a cross mark following either one or the other of the foregoing propositions, and said ballot shall have printed upon the face thereof instructions to the voters, worded as follows:
"To vote for or against an increase in the number of directors of the .............. Irrigation District, a voter shall place a cross mark in the space at the right of the words expressing his wish either 'FOR' or 'AGAINST' such increase."
C.R.S. § 37-43-107