How to use different files for multitarget build?

I'm using Costura Fody to merge all project references to single DLL. My solution is targeting Net45 and netstandard2.0, and includes different references for each one. So FodyWeavers.xml should also list different assemblies, but I can't figure out how to do that. I can't seem to find any way to set target inside FodyWeavers.xml, so another option would be to use two different files, but is that even possible?

Here is what FodyWeavers.xml looks like:

<?xml version="1.0" encoding="utf-8"?>
<Weavers xmlns:xsi="" xsi:noNamespaceSchemaLocation="FodyWeavers.xsd">

System.Text.Encoding.CodePages is only available in Netstandard and Fody gives an error when tries to compile it for Net45. And if I remove it, then it's not included in Netstandard build.