The way to use a .msp file in Skyline is to add it as a library.
That is, you go to the "Library" tab at "Settings > Molecule Settings" and push the "Edit List" button and then "Add".

Unfortunately, when I do that with the "IgG_Glycopeptide _HCD_V1.msp", I see a bunch of messages in the Immediate Window that say things like:
Missing details for TKPREEQYNSTYR_G33100/4/E12 at line 4, this entry will be ignored

It appears that every entry ends up getting ignored because when I go to:
View > Libraries > Library Explorer I do not see anything in that library.

Is that the same sort of issue that you are running into?
I am not the expert on .msp files in Skyline but I could try to find someone to investigate this.
-- Nick

Hi Nick, thank you for your response. I did not see the immediate window messages but indeed get an empty library as a result. I wanted to use this library for the IgG control I am including in my glycopeptide analysis workflow, so I would appreciate you looking into this. Alternatively I can produce my own library with DDA measurements. I read in another topic that the .msp format pops up in different variants as well, so I imagine having a robust .msp reader is tricky.

Thanks,
Tom