If you want to copy only a single GPG key, at first you have to
export it from the source machine and then
import into the destination. This is what --export and --import options are intended for. Here is a quick howto:
Code:
# In the source machine:
gpg --output <name_of_file_with_public_key>.gpg --armor --export <name_of_key_to_export>
gpg --output <name_of_file_with_secret_key>.gpg --armor --export-secret-key <name_of_key_to_export>
# In the destination machine:
gpg --import <name_of_file_with_public_key>.gpg
gpg --allow-secret-key-import --import <name_of_file_with_secret_key>.gpg
where the parts highlighted in grey are the custom parts. Moreover, you can easily find the name of the current GPG keys using
Hope this helps.