Open Adobe Acrobat 8 Professional, and start a new blank PDF, or open an existing PDF from your files to which you want to insert a date field.
Select the "Text Field Tool" from the Forms toolbar. It is the sixth button from the left side of the toolbar and is depicted by a box with the letter "T" inside of it.
Use the click and drag on the PDF where you want to insert the date field. The "Text Field Properties" dialog box will pop up when you are finished drawing.
Click the "General" tab from the top of the "Text Field Properties" box and set the general settings. Type "Today" in the "Name" text box and add a checkmark for the "Read Only" option.
Choose the "Format" tab from the top of the dialog box. Choose "Date" from the "Select format" drop-down list. The "Date Options" text box will display, and you can click to choose how you want the date displayed.
Type "var f = this.getField("Today"); f.value = util.printd("mmm/d/yyyy", new Date());" (without outside quotes) in the textbox of the dialog box. Click "OK" and "Close" to close the two open dialog boxes. Now each time the page is open the current date will be displayed in the date field.
If you don't see the forms toolbar, you can choose the "View" menu, point to "Toolbars" and click "Forms" to display it.