Where the button is available by default

The button is already available on Campaign and Account records once the package is installed. If you cannot find it after installation, drag the button from the page layout to make it available to users.

Create the button for a custom object

1. Log in to Salesforce, go to Setup > Create > Objects, and select the object you want to create the button on.
2. In the Buttons, Links and Actions section, click New Button or Link.
3. Enter SMS on Related List as the label.
4. Select Detail Page Button as the display type.
5. Set Behavior to "Display in new window".
6. Set Content Source to "URL".

Add the formula

Copy the code below into the formula editor, replacing <Sobject-API-NAME> with the API name of the object you are creating the button on:

/apex/rsplus__VtRelatedListSMSsendingVfLite?pid={!<Sobject-API-NAME>.Id}

Click Save.

Add the button to the page layout

Edit the page layout for the object and add the new button so it is available to users.