It sounds like you have DDA peptide search results for one set of runs, and you would like to use those search results to improve your analysis of some other PRM runs.
If that's the case, then I would recommend that you use the "Import DIA Peptide Search" button on the Skyline Start Page. (The Start Page is the first thing that comes up in Skyline. If you have unchecked the "Show start page at startup" box on the Start Page, you can also get to it from Skyline by going to "Help > Tutorials", and then switch the tab to "Start".
When you get to the "Configure Full Scan Settings" of the wizard, you probably want to set your MS/MS filtering Acquisition Method to "Targeted" (which means "PRM").
The last step of the wizard asks you to provide a FASTA file so that Skyline knows which peptides you are interested in. If your Skyline document already contained the peptides you were interested in, you can cancel out of the wizard at that point, and instead use the "File > Import > Results" menu item to tell Skyline to extract chromatograms from your PRM data files.
Hope this helps. If this wasn't helpful, you might have to give us more information about what sort of data files you have, and what your Skyline document looks like so far.
The Basic Data Acquisition tutorial might have some useful information in it for you:
This is an old tutorial which needs to be updated. A lot of the settings that are used throughout the tutorial are not the settings that we currently recommend. For instance, we now recommend that you use "Centroided" as the "Precursor mass analyzer" and "Product mass analyzer" (page 4 of the tutorial). But, the tutorial might have useful information in terms of using DDA search results with data from other runs.