SyntaxAnnotationWithKind.cs

AdhocWorkspace workspace = new AdhocWorkspace();
Project project = workspace.AddProject("Test", LanguageNames.CSharp);

string annotationKind = "SampleKind";
var syntaxAnnotation = new SyntaxAnnotation(annotationKind);
var classDeclaration = SyntaxFactory.ClassDeclaration("MyClass")
	.WithAdditionalAnnotations(syntaxAnnotation);

var compilationUnit = SyntaxFactory.CompilationUnit().AddMembers(classDeclaration);

Document document = project.AddDocument("Test.cs", compilationUnit);
SemanticModel semanticModel = await document.GetSemanticModelAsync();
var newAnnotation = new SyntaxAnnotation("test");

//Just search for the Kind instead
var root = await document.GetSyntaxRootAsync();
var changedClass = root.GetAnnotatedNodes(annotationKind).Single();

var symbol = semanticModel.GetDeclaredSymbol(changedClass);