Is there an up-to-date document detailing how to apply magnetic base station corrections to surveys?

I can't seem to find a document that explains how one goes about applying a base station correction to a magnetic UAV survey. 

I have an excel file with raw recorded base station values and the time the values were collected (in Unix time). I also have a database with the survey data and the time of collection (also in Unix).

There are documents online and on the Seequent site that explain how you might do this, but they all either seem to reference a version of Oasis Montaj which has since been updated, or they require me to basically know what formula ought to be used to apply a base station correction, which is part of the reason I'm using Oasis Montaj in the first place (because I don't know exactly how it should be done, and I expect the correct approach is pretty universal in magnetic surveying).