To create a space between 2 fields, create an invisible Custom Field in between them:
1. Navigate to Customization > Lists, Records, & Fields > select the type of Custom Field > New.
2. Enter Label for the field.
3. Type = Inline HTML
4. Under Applies To > mark the box that corresponds to the record or transaction type where you want to place the custom field.
5. Under Display > Subtab = select the subtab where the user want to place the custom field.
6. Click Save.
Customize the Custom Form to set the position of the field.
1. Customize the Custom Form > under Screen Fields tab, drag the custom field created above in between the 2 fields where the space should be created.
2. Assign an appropriate Field Group.
3. Make sure Show = checked.
4. Click Save.