Switch to Layout mode (View ▸ Show Layout) and then choose the line segment from the Shape toolbar item. While selected, visit the Arrange tab and set wrap to None. Switch back to the Style tab, and set the line segment color and thickness to taste. No shadow or reflection will be necessary.
Stretch the line segment from margin to margin using the blue guides as your terminus indicator. Drag the line segment down to just above your footer top border. From the Arrange menu, choose Section Masters ▸ Move Object to Section Master. The line segment will now appear in its footer position on every page in your document. Revisit the preceding menu hierarchy if you want to edit that line segment.
Finally, from the View menu, Hide Layout.