How to create delegate of Func when b has parameters

I am trying to call a method that takes in a function, but using relection. I've gotten it to work when the method is parameterless but I can't figure out how to invoke it when there are arguments. This is a contrived simplified example, but this boils down the problem. I will not know the arguments to Add until runtime.

Any pointers? Do I have to use expression trees? Is there an easier way to do this?

public void Main()
{
    //works
    CallFunction(typeof (Processor), "Count");
    //I don't understand what I need to modify to make add work
    CallFunction(typeof (Processor), "Add");
}

public void CallFunction(Type type, string methodToCall)
{
    var targetMethod = type.GetMethod(methodToCall);
    var constructedType = typeof (MethodCaller<>).MakeGenericType(type);
    dynamic target = Activator.CreateInstance(constructedType);
    var method = constructedType.GetMethod("Do").MakeGenericMethod(targetMethod.ReturnType);
    var func =  typeof (Func<,>).MakeGenericType(type, targetMethod.ReturnType);
    var toCall = Delegate.CreateDelegate(func, targetMethod);
    method.Invoke(target, new object[] { toCall });
}

public class Processor
{
    public int Count()
    {
        return 1;
    }
    public int Add(int toAdd)
    {
        return 1 + toAdd;
    }
}

public class MethodCaller<TParm> where TParm : new()
{
    public TResult Do<TResult>(Func<TParm, TResult> func)
    {
        return func(new TParm());
    }
}