If you can't use the exemption due to lack of the required documents, you can elect to determine your credit by calculation on form 1116 in lieu of the default exemption.
In forms mode, open up the "Federal Information Worksheet." Scroll down to Part 6 and at the 5th paragraph see the "Foreign Tax Credit Form 1116". Checkmark the box to file form 1116.
TT will make the calculation and attach form 1116 to your return.
