View Source code for .net core application

 I have a .net core application that complies to a .dll.  Visual studio does not generate a pdb file (at least not where I can find it).  I can see the "decompiled source" but when I run the line by line profiling I think it needs to link to the actual source files or the pdb file.  

I've looked through the documentation on Folder Substitutions but it's pretty unclear what would be the Source Folder and Target Folder or if it's talking about the solution folder or the project folders or if it even actually applies for what I'm trying to do.