Either the JDBC driver genuinely cannot be found, or more likely perhaps, your JDBC settings in Entity Modeler are incorrect.
On Mac OS X, the /Library/Java/Extensions directory is provided for extensions to the core Java API, and is thus the appropriate place for JDBC drivers.
Put your JDBC drivers into the /Library/Java/Extensions then, and they should be picked up automatically by Eclipse.
Check your classpath settings in Eclipse as follows:
Check that the settings for your JDBC driver are correct; these details are provided by the suppliers. MySQL settings are shown in the screenshot (see screenshot). Note that drivers have peculiar use of capitalization, and that this must be correct for the driver to function!
Derby JDBC driver settings:
Embedded Derby, how is it done?
How do you set property derby.system.home so Entity Modeler can be used?
MySQL JDBC driver settings:
URL: jdbc:mysql://<hostname>/<database_name>. eg. jdbc:mysql://localhost/authors
Driver: com.mysql.jdbc.Driver
OpenBase JDBC driver settings:
URL: jdbc:openbase://<hostname>/<database_name>. eg. jdbc:openbase://localhost/authors
Driver: com.openbase.jdbc.ObDriver
FrontBase JDBC driver settings:
URL: jdbc:FrontBase://<hostname>/<database_name>. eg. jdbc:FrontBase://localhost/authors
Driver:
Postgresql JDBC driver settings:
URL: jdbc:postgresql://<hostname>/<databasename> eg. jdbc:postgresql://localhost/authors
Driver: org.postgresql.Driver
Plugin: Postgresql
H2 JDBC driver settings:
URL: jdbc:h2:~/<databasename>