Xft font with different pixelsize?

[Yuan MEI]

Hi,

    I just tried Emacs-23 with xft.  Previously I used X core font,

.Xdefaults:
Emacs.Fontset-0: -*-bitstream vera sans 
mono-medium-r-normal-*-12-*-*-*-*-*-fontset-utf8,\
    utf-8:-*-wcd-medium-r-normal-*-14-*-*-*-*-*-iso10646*-*
Emacs.Font: fontset-utf8

.emacs:
(set-fontset-font
    "fontset-utf8" 'han
    "-*-wcd-*-*-*-*-14-*-*-*-*-*-gbk-0" nil 'prepend)

My purpose is to use pixelsize 12 for normal text and pixel 14 for
another language

And for xft, I tried
(set-fontset-font
   "fontset-utf8" 'han
   '("WCD" . "unicode-bmp") nil 'prepend)
which works but the pixelsize is 12 as used for default font
"bitstream vera sans mono".  And ("WCD-14" . "unicode-bmp") does not
work at all.

So, is there anyway to set different pixelsize for different Unicode
range characters using xft?

Thanks.

-- 
Yuan MEI