There should be a page of Supplemental Info with your brokerage statement that gives some detail on how much of your dividend income is from foreign investments. It may list amounts/countries/percentages. If not, you may be able to access this info online at broker site, or reach out to your broker.
Once you have an amount that is Foreign Income associated with your Foreign Taxes, in the Foreign Tax Credit section, you can list the country as RIC (regulated investment company) and enter the total. You don't need to break out the various countries/amounts.
Choose the Foreign Taxes option under Estimates and Other Taxes Paid, in the Deductions and Credits section of TurboTax:

Indicate that you have already entered your 1099 forms with foreign taxes paid. Choose the foreign tax credit option in place of the deduction. Choose the passive income option if your income is non-business or non-employment related income. Assign a country for your income and report the foreign income amount.
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