I am sorry but I am confused. Can you clarify how you want the workflow rule to be triggered?
Here are the ways you can use an event triggered workflow rule to send an email or SMS message.
An event triggered workflow rule can be run on the server each time a data change is sent from the client to the server. You can write an expression that precisely controls which changes will trigger each workflow rule.
Typically, the workflow rule is triggered when a record is added, updated, or deleted to a table, and that change is “Synced” to the server. The workflow rule on the server, detects the change. The workflow rule is triggered, and it produces an email message which it sends to the email addresses you specify.
If you want to trigger a workflow rule based on clicking a button on the client, you can do this as described in the article I cited above. Essentially, the button click causes a data change that is “Synced” to the server. Just as described above, the workflow rule on the server, detects this change. The workflow rule is triggered, and it produces an email message which it sends to the email addresses you specify.