Any document, text file, picture or report can be printed as PDF document, you just need a software that either has direct PDF support or at least supports printing with a physical printer. The first options is pretty straightforward, for the second you will need to install a virtual PDF printer.
It's worth mentioning that almost every (if not every) tax preparation software supports PDF export, so conversion of .txf files to a .pdf document should not be a problem.Open TXF file Open PDF file
A popular tax preparation software from HRB Digital
A tax preparation software
A Mac version of popular tax software
A tax preparation software developed by Intuit
A popular tax preparation software