The broker will indeed typically give you the foreign income amount. It does not have an official box on the 1099-Div but is usually somewhere in the supplemental information (which is not sent to the IRS). It is not always easy to find. You can also try looking at the ETF website for the tax info for that particular fund.
The investment that paid the foreign tax should disclose somewhere it's foreign income. Other investments might not disclose or might not have any foreign income.
If the ETF did not do the selling but you sold the ETF then the capital gain won't be foreign income. If the ETF paid dividends or capital gains distributions and was taxed on those you'll see both the tax listed on the 1099 and somewhere the amount of foreign income.
If you can't find something that says it is foreign income, I think you have to conclude that it is not.
If your only foreign tax is from passive investments shown on 1099s or K-1s and it is less than $300 ($600 joint) you don't need a 1116 and it won't matter what you put down for foreign income because the section 904 proportionality won't apply. See https://www.irs.gov/pub/irs-pdf/i1116.pdf page 1.
**Mark the post that answers your question by clicking on "Mark as Best Answer"