I am a foreign national residing overseas with some investment income in the US. Which IRS form / TurboTax form should I use?

[SundayInSalem]

A foreign national living overseas would use Sprintax.com, not TurboTax, to file a tax return for US investment income. Use Form 1040NR. You can't do this in TurboTax but it's available with Sprintax.com.

Nonresidents will only pay US tax on US source income. Refer to the list on this link to see what's taxable: 

Nonresident Aliens - Source of Income