public RelationshipClassToken Create( 
   RelationshipClassDescription relationshipClassDescription
)

public void CreateRelationshipWithRelationshipRules(SchemaBuilder schemaBuilder)
{
    // Creating a 'BuildingType' table with two fields - BuildingType and BuildingTypeDescription
    FieldDescription buildingType = FieldDescription.CreateIntegerField("BuildingType");
    FieldDescription buildingTypeeDescription = FieldDescription.CreateStringField("BuildingTypeDescription", 100);
    TableDescription buildingTypeDescription = new TableDescription("BuildingType", new List<FieldDescription>() { buildingType, buildingTypeeDescription });
    TableToken buildingtypeToken = schemaBuilder.Create(buildingTypeDescription);

    // Creating a 'Building' feature class with three fields - BuildingId, Address, and BuildingType
    FieldDescription buildingId = FieldDescription.CreateIntegerField("BuildingId");
    FieldDescription buildingAddress = FieldDescription.CreateStringField("Address", 100);
    FieldDescription usageSubType = FieldDescription.CreateIntegerField("UsageSubtype");
    FeatureClassDescription featureClassDescription = new FeatureClassDescription("Building", new List<FieldDescription> { buildingId, buildingAddress, buildingType, usageSubType }, new ShapeDescription(GeometryType.Polygon, SpatialReferences.WGS84));

    // Set subtype details (optional)
    featureClassDescription.SubtypeFieldDescription = new SubtypeFieldDescription(usageSubType.Name, new Dictionary<int, string> { { 1, "Marketing" }, { 2, "Utility" } });

    FeatureClassToken buildingToken = schemaBuilder.Create(featureClassDescription);

    // Creating a 1:M relationship between the 'Building' feature class and 'BuildingType' table
    RelationshipClassDescription relationshipClassDescription = new RelationshipClassDescription("BuildingToBuildingType", new FeatureClassDescription(buildingToken), new TableDescription(buildingtypeToken),
      RelationshipCardinality.OneToMany, buildingType.Name, buildingType.Name)
    {
        RelationshipType = RelationshipType.Composite
    };

    // Adding relationship rules for the 'Marketing' subtype
    relationshipClassDescription.RelationshipRuleDescriptions.Add(new RelationshipRuleDescription(1, null));

    schemaBuilder.Create(relationshipClassDescription);
    schemaBuilder.Build();
}