Can someone help me determine this 3d object for .999 fine silver Size?

Can I use that tool if I do not have RHino?

You’ll need Rhino to use that tool. I don’t know which version of Rhino you are using, but the scale to target mass works in 6 & 7 (I don’t have Rhino 5 anymore so I can’t test it.)

Do you know if this will work in rhino 7 EVALUATION?

I presume it would work with the eval. You just type in Toolbar, then File, Open and select that file.