Important Note: The "Stakeholders" feature is involved in signing workflows. This is a premium feature paid monthly: 7-day free trial, cancel anytime, activate it with a Booster or a Platinum plan.
You can add as many external signature placeholders as needed in your e-contracts. For doing so, you'll need to combine the stakeholders feature with the e-contract capability.
If you have multiple signers and need to create a signing workflow, follow this article.