If you want to trace objects or make edits on top of your imported PDF, you'll want the scale of the PDF or image to match the scale in your document.
To help you scale the PDF or image, we'll want to match a line drawn in SmartDraw with an object with known dimensions from the imported file. So before we can resize the image, pick an object that you know the dimensions of to use as a reference.
If you started with a Google map capture, you can use the scale shown in the lower right corner of the map.
If you are working with a blueprint from somewhere else, it will either have a scale itself or the labels on rooms or objects should be your guide.
Once you picked your reference object on the imported visual, draw a line that matches the length of that specific segment using your document scale.
The final step will be to resize the image so that the object in the drawing matches the width of the guide line.
Learn more about matching the scale of your imported PDF here.