In the 3D Text dialog, set it to not filled and not extruded.
Now go ahead and create the text and put it on the face into which you want to engrave it.
For this exercise, it’s good to work with profiles on so you can clearly see the distinction between dark profiles and light edges.
Now right-click the text object and click Explode. This has the effect of placing the raw geometry of the text right on the face, which is necessary to pushing it in. Now observe: you may see that most of the text is made of fine, light-colored edges. That means they have cut into the face, which is good. But you may see a couple or few places where the lines are dark, probably on closed internal loops like in a capital A or lower case e. These profile lines need some help in order to cut into the face. So, with the Line tool, trace over one segment, endpoint-to-endpoint, of a dark loop. That should fix it. Now fix them all.
When all the edges are light (fine), you can push the letters into the face. You can push the first letter to the depth you want, then double-click the rest to repeat the same depth.