How can I insert a rectangle?

I'm creating a Word document where I would like to have a rectangle beside each numbered line for people to initial, indicating that they're read and understood that item. I know I can just add a line, but I thought it might look more professional to have a rectangle. I've looked in all of the "insert" menus, and cannot locate one. Does anyone here have a suggestion as to what I can do?

Thanks,
Carmen