To selectively reverse engineer specific tables, you will need to use the Complete Compare function.
First of all you will need to create a blank physical model, then launch Complete Compare (Actions->Complete Compare). The blank model will be selected as the “left” model in the comparison and you need to choose to load the “right” model from the database.
Hitting “Load” will start the Reverse Engineering process.
On completion of the Reverse-engineer, select the Right Object Selection step from the left-hand side of the wizard. You will then be able to choose the tables you wish to include in the model, either by “sets” (e.g. all tables in a particular schema), or by selecting specific tables from the list on the right.
When you have selected the tables you want to include, hit “Compare”. In the resulting Resolve Differences dialog, select the Model node and then the left arrow to move the selected objects into the new model.
When everything has moved, click “Finish” then “Close” and you will be prompted to close the reverse-engineered model without saving. OK this (this is a throw-away model just for the purpose of the comparison) and you will be left with a model containing the objects you selected.
The diagram you see will probably be empty, so you will need to open the Diagram Editor (Diagram->Diagrams) and check the Auto-populate box to display the tables on your diagram and close this dialog. You will also need to layout the diagram (Diagram->Layout and choose an option).