How to use Crypto++ to encrypt file using private key (and decrypt using public key)?

[Seo, Eun-taek]

I've read RSA (for example) can be used to encrypt file using private key and decrypt 
using public key.
I distribute some files to clients and I don't want them to modify my  files. Of 
course, file modification check
can be done using digital signature or etc. But I want to use RSA public key system to 
do this work.
Simply using public key for decryption and private key for encryption seems not 
working.
How can I use Crypto++ to do such a thing?

Thanks in advance.