You can configure Horizon Client to select a local certificate or the certificate on a smart card when you authenticate to a server by setting a preference. If this preference is not set (the default), you must manually select a certificate.
Prerequisites
For this setting to take effect, smart card authentication must be configured on the server and only one certificate must be available on your client system or smart card. If you have multiple certificates, Horizon Client always prompts you to select a certificate, regardless of how this preference is set.