I have to presume you are preparing a return for a separate taxable entity and not a grantor trust (the latter of which is typically treated as disregarded for federal income tax purposes).
The K-1s will not show any figures for distributions of trust corpus (principal). In fact, if that is all you are distributing, you may not even be required to file a Form 1041.
A 1041 is required to be filed if the trust has any taxable income for the tax year or gross income of $600 or more (regardless of taxable income), and a couple of other rare instances.
See https://www.irs.gov/instructions/i1041#idm140229124997744
If the trust had income (or gain from the sale of securities), then you need to make a distribution in the Distributions section of the program.
