The only way i have been able to achieve this is by using Unicode. Unfortunately you are limited to only certain standard fractions. ¼,½,and ¾.
To do this:
create an annotation with the text that you want it to say.
then where you want the fraction to appear hold down the alt key while pressing the corresponding number sequence below.
0188 = ¼
0189 = ½
0190 = ¾
Hope this helps!
A man should look for what is, and not for what he thinks should be. -Albert Einstein
A person who never made a mistake never tried anything new. -Albert Einstein