If your 1099-DIV does not list the countries that you paid your foreign tax on the dividends received, then you need to visit the Vanguard fund website for VTIAX. The Vanguard website should provide this tax information. If this is not listed on the website, then contact Vanguard for this information.
You will not select the foreign countries where you lived as that does not answer the question about where the foreign taxes were paid for the dividend income received from your investments.
However, when you report any foreign taxes you paid for the wages you received abroad, then at that time you will indicate the two countries you paid foreign tax to - if you paid foreign tax on the income received for working in that country.
