While it is typically only necessary for one owner or agent of the owners to sign a lease in order for it to be legal and binding, spouses can include both of their names on a digital signature.
First, proceed to the lease signing as standard.
From the Leases tab press Sign Lease.
When completing the signature, enter both names into the Name field.
This is how the digital signature will display on the lease.
The lease and PDF file copy will show the both owners on as signatories.