It appears that this limitation has been fixed in Skyline-daily.
You can install Skyline-daily using the "Skyline-daily (beta)" button on the Skyline page:
https://skyline.ms/project/home/software/Skyline/begin.view
You can have both Skyline and Skyline-daily installed on your computer at the same time.
Documents that you create using Skyline-daily cannot be opened by older versions of Skyline, but you can use the menu item "File > Share" to create something that will be able to be opened by older versions.
Skyline does not hit the "Out of Memory Error" when Skyline is first reading the CSV file. Instead, the problem happens when Skyline is trying to record in the audit log what text was being imported. The exact text that Skyline tries to write to the audit log depends on what columns you have selected in the "Assay Library: Identify Columns" window. The Audit Log is the thing that you see if you go to "View > Other Grids > Audit Log".
We have fixed things in Skyline-daily so that the text that you are importing does not get written to the audit log if you are importing from a file. The text only gets written to the audit log if you are pasting from the Clipboard.
I see that you are running Skyline 21.2. The latest version of Skyline is 22.2. We always recommend that you run the latest released version of Skyline unless you are trying to reproduce results from older experiments.
Skyline 22.2 probably still has the same Out of Memory error that you are seeing with Skyline 21.2, You will need to use Skyline-daily to be sure that you don't run into this error.
I made a slightly smaller version of that file which you can download from here:
https://proteome.gs.washington.edu/~nicksh/rita/MouseRefSWATH_iRT_smaller.csv
I am not sure whether this smaller CSV will actually help you with the bug that you are hitting.
By the way, if you ever need to edit an enormous CSV file like this again, I recommend the program "EmEditor professional":
https://www.emeditor.com/
-- Nick