How can I format a text box such that the box for text entry is at the very end of a two-line sentence?

I am trying to create a fillable PDF form but need the text box to show up at the end of a sentence. Here is the sentence:

You are entering into a rental agreement template with Global Parts, Inc. for the items as defined by your Purchase Order number _____

Where the underline is I want to place a text box but when I try to create the text box the sentence wording is scrunched up to the left side of the text box. I want the text box inline with the sentence, not off to the side of the sentence.

We have the widget Narrative Fields. This will create a blank area where users can enter the text to fill in.

Please let us know if this helps.