How to encrypt and sign files

Currently running Ensemble on Red Hat Enterprise Linux Server release 7.7

One of our clients is requesting files sent to their SFTP site be encrypted with their PGP public key and digitally signed with our PGP private key

We have created a custom class that includes the following command to encrypt the files

if (pAction = "Encrypt") {
// Find the Key ID from the Keyname
set tKeyId = ..GPGKeyLookup(pKeyName, ..#PUBLICKEYLUT)
set tCmdLine = "gpg --homedir "_pGPGhomedir_" --always-trust -r """_tKeyId_""" -o "_pOutFileName_" -e "_pInFileName
}
// Execute the command to generate the output file
write !,"Calling command: "_tCmdLine
do ##class(JMH.Utils.Utilities).RunCmdLine(pWorkarea, tCmdLine, .tOutput)
write !,"tOutput: "_tOutput

We want to update the gpg command to digitally sign the encrypted file

Would appreciate any suggestions on how to edit the gpg command to digitally sign a file