There are two different sets of keys for 32 bit and 64 bit applications.

32 bit:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\MAIN\FeatureControl\FEATURE_BROWSER_EMULATION

Value Key: yourapplication.exe

64 bit:

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Internet Explorer\MAIN\FeatureControl\FEATURE_BROWSER_EMULATION

Value Key: yourapplication.exe

The value to set this key to is (taken from MSDN here) as decimal values:

9999 (0x270F) 
Internet Explorer 9. Webpages are displayed in IE9 Standards mode, regardless of the !DOCTYPE directive.

9000 (0x2328) 
Internet Explorer 9. Webpages containing standards-based !DOCTYPE directives are displayed in IE9 mode.

8888 (0x22B8) 
Webpages are displayed in IE8 Standards mode, regardless of the !DOCTYPE directive.

8000 (0x1F40) 
Webpages containing standards-based !DOCTYPE directives are displayed in IE8 mode.

7000 (0x1B58) 
Webpages containing standards-based !DOCTYPE directives are displayed in IE7 Standards mode.

寫的很詳細

修改Htm頁面的方法之一是，在Head->Title下新增<META http-equiv="X-UA-Compatible" content="IE=9" > </META>，這樣可確保HTM頁面工作在IE9標準文件模式下。