You will want to make the macro like the following, however, just in case you want to use the spell on your target.

For example, you want to DPS while still targeting your tank;

/macroicon "Stone"
/ac "Stone" <t>
/ac "Stone" <tt>

So that you can use the same stone macro if you want to target the mob by itself. (macroicon makes it look like the skill icon)