Auto text resize in multiline text field is not working on Iphone/Ipad

I have a fill-able PDF with a multi line text input field in which the font automatically resize to keep all the text enter to fit in the text box.  This works just fine on PC's and Kindle Fires, however the text font size does not resize in Acrobat Reader for the Iphone and Ipad.   Also you can not enter text after you have filled the text box with text, meaning it acts like it is fixed character limit instead of expandable.  Appreciate any help, I am not have any luck finding a solution with google searches and forumn searches.