You're getting an unusual error. I suggest we backtrack a bit...
1. If you just double-click the Distribution\ExcelDna.xll, does it open and make an =AddThem(...) function available in your Excel?
2. When you get the ExcelDna.Loader error, could you perhaps have a mismatched version of ExcelDna.Integration and ExcelDna.xll in your output directory? You don't actually need ExcelDna.Integration.dll in your output directory or to redistribute it. The
easiest is to set the reference to ExcelDna.Integration.dll as "Copy Local = false".
I suggest you get everything working without the ArrayResizer first.
For the ArrayResizer you need to call ExcelAsyncUtil.Initialize() from a macro context. Easiest is just to define a class in your project that implements the IExcelAddIn interface, and then put the call to ExcelAsyncUtil.Initialize() in the AutoOpen().
An Excel-DNA "Add-In" is the combination of your renamed copy of ExcelDna.xll (maybe called MyCoolAddIn.xll), a MyCoolAddIn.dna file and any .dlls you might need.
There is no dependency on the Rx libraries for the basic Excel-DNA version, but if you want to use the
RxExcel example then you need to reference some Rx libraries. So just to export some functions, and even use the Resizer, you need no reference to Rx.