Within the vertex shader, multiply the input position coordinates by your scale value (1.0 = 100%) before transforming them. For example: most vertex shaders contain a line somewhere along the lines of:
OUT.OPos=mul(IN.Pos,WorldVP);
That line is responsible for transforming vertex position coordinates from object space into clip space. To add scaling, just multiply
IN.Pos by your scaling value before its multiplied by the transformation matrix.
;(within the "Tweakables" section)
float Scale = 1.0f;
;(within the vertex shader)
OUT.OPos=mul(IN.Pos*Scale,WorldVP);
