you can usually use Tags/Fit to Object, Fit To Image to adapt an image to geometry but that works without the alpha, the extra image outside the alpha boundaries will throw that off. It will probably be necessary to use the controls in the Texture Tag to get it to match like you want. Make sure Tile is unchecked then use Length U/V and Offset U/V to move the image where you need it to be. Judging by your image you will likely have to increase Length U and adjust Offset U to get it placed, the V looks pretty close already and should only require minor tweaking.