Mutual TLS reference architecture

TLS is normally done by certificates.
So you'd need a cert on the VS and one on the client. 
And you can then tell the server config to enforce the trust,

The normal issue here is managing and maintaining the certificate on the client's.

It can also be done between f5 and the web servers, as there internal and fixed that's normally a little easier!
Just make sure the certs are kept up to date otherwise they'll all die!
Normally worth renewing each certificate at last a week a part on each web server to try to manage that.