Use composer require to add PHP/SAP to your project. Depending on the
PHP module you need to require a certain PHP/SAP composer
package.
The namespace of the library is \phpsap\saprfc.
In order to call a SAP remote function, you need to configure a connection and then invoke a function.
In case you want to use the SAP remote function API like any other PHP class,
you can extend AbstractRemoteFunctionCall and you will get
implicit documentation of your SAP remote function call parameters and the
return value(s).