In GeoDirectory Advanced Search, fields you add to the search form go into a filters panel. Visitors open it with the filter (cog) button next to the search button. To show a select or multiselect field as a dropdown in the search bar itself, move it to the main search bar.

Put the field in the main search bar

1. Go to Places > Settings > Search (or the Search tab of your own post type).
2. Open the field you want, for example your multiselect field.
3. Turn on the option to show it in the main search bar, and set its position in the bar.
4. Save the field.

In the main bar every field shows as a single dropdown, the same style as the category dropdown. Select, multiselect, radio, checkbox, category, date, time, open hours, rating and distance fields can go in the bar.

Choose how a field looks in the filters panel

For fields that stay in the filters panel, the Input type setting decides how the options are shown: Dropdown, Checkboxes, Radio buttons or Links. Use Checkboxes if visitors should be able to tick more than one option.

Keep the filters panel open

If you’d rather keep the fields in the filters panel but not hide them behind the button, edit your GD > Search block or widget and set Open customize filters to Always open. To show only the filters, without the main bar, set Show to Advanced filters only.

More detail is in the Advanced Search setup guide and How to add a filter to the main search bar.