Reference Tracker can import reference data created in other software, or downloaded from online services, via the standard BibTex and RIS file formats.
You can open a BibTex file (with the filename extension '.bib') or RIS file (with the extension '.ris') by double-clicking on them in the Finder, or by dragging them on to Reference Tracker's App Icon. The data from the file will be added into a new Reference Tracker document, which you can then save in the Reference Tracker file format - the original BibTex or RIS file will remain untouched.
You can also import the contents of a BibTex or RIS file into an existing Reference Tracker document, by selecting the 'Import > BibTex/RIS file...' from the 'File' menu. Select the file in the open panel and it's contents will be imported into your document.