How to make silver manganese alloy?

 I would like to make an alloy of Silver & Manganese - Silver 84 - 86%, the remainder Manganese with other impurities max. of 0.15%. How do I go about this?

Yep size is important. I'm going to assume that you are looking at mid range.

I would suggest melting in a furnace though, gas is relatively fast, using a clay graphite crucible. Stirring with a green stick when the charge is molten.

When you see alloy percentages it's always by weight.

You always charge your crucible with the lowest melt point metal first, and put the higher melt point metal on top. This in effect lowers the melt point of the higher melt point metal.
Depends on how much you want to make. In small quantities, measure out the appropriate weights of fine silver casting shot and manganese flake, and melt them in an properly flux-treated ceramic crucible, using either a crucible furnace or a handheld torch. To reduce oxidation, an oxy-hydrogen torch will probably give the best results. Use a reducing (fuel-rich) flame.
For larger quantities you might want to look into an induction melter.