修改PDF表单字段中的字符间距

I'm trying to build a web app to programmatically fill out a PDF form. I am going to configure my form first in Adobe Acrobat, then write a Java app with iText to fill out all the form fields via user input from the web. The base form I need to fill out comes from the US government. They created form fields with extremely large kerning (character spacing) values I need to change. However, there appears to be no way to modify this value in the Acrobat UI. I'm trying to build a web app to programmatical