To use a different font you can change the value in the globals file from this:
$WAGLOBAL_Captcha_Font = "Fonts/MOM_T___.TTF" ;
To match one of the other fonts that are available in the WA_ValidationToolkit > Fonts folder.
If you can see the captcha on the the default page but not the one you add to make sure that the paths for the captcha image match what is on the page, by default the image looks like this:
You need to make sure it is in the same directory as the WA_ValidationToolkit folder.