(1) This rule applies where, in a proceeding for a grant, an applicant seeks to prove a will and:
(a) the will appears to have been signed by a blind testator;
(b) the will appears to have been signed by an illiterate testator;
(c) the will appears to have been signed by another person by direction of the testator; or
(d) there are circumstances which raise doubt whether the testator, at the time of execution of the will, knew and approved of the contents of it.
(2) An applicant shall furnish evidence on affidavit to establish that the testator, at the time of execution of the will, knew and approved of its contents.
(3) Where the evidence adduced pursuant to subrule (2) is that of an attesting witness or other person present at the time of execution, his affidavit shall state the manner in which the will was executed.