There are several methods to accomplish it:
- Create a character style with underline. Apply it to a tab character or to several fixed width spaces. (Don't use normal space for that purpose). You can automate it with GREP.
- Draw a line, copy it into you clipboard, change to your text curser, click on the position in text, with the direct selection tool you can adjust the length. With Object > Anchored Object Options you can adjust them vertically, you can use also a Character Style to adjust it, an object style is recommended to make late global adjustments to stroke width and color.
Yes, of course. I wish my brain worked! Used method 1
Thanks so much for your reply.
You can create the form fields in InDesign CS6 or CC which will be imported into Acrobat Pro for refinement. You can do this with the Buttons and Forms panel.
It's not necessary to create rules which Acrobat Pro turns into form fields. You can design the form fields yourself which is more flexible.
Here is a video which introduces you to how it is done:
Here is the CS6 Help file on creating forms:
WOW, thank you everyone for your wonderful feedback. Truly helpful.