Example of a working gmod render target

render-target-example.lua

local texture = GetRenderTarget('uniquert'..os.time(), 512, 100, false)

local mat = CreateMaterial("uniquemat"..os.time(),"UnlitGeneric",{
	['$basetexture'] = texture,
});


hook.Add('HUDPaint', 'sao', function()
	local scrw, scrh = ScrW(), ScrH()

	-- this is a perfect render target dealio.
	render.PushRenderTarget(texture)
	cam.Start2D()

	render.OverrideAlphaWriteEnable(true, true)

	cam.End2D()
	render.PopRenderTarget()

	mat:SetTexture('$basetexture', texture)
	surface.SetDrawColor(255,255,255)
	surface.SetMaterial(mat)
	surface.DrawTexturedRect(0, 0, 512 , 100)
end)

I don't understand how to use this. Where are you giving it any origin or angle with which to use the RT?