With 1.0.x to create a FloatingActionButton or the ExtendedFloatingActionButton you can use something like:

val onClick = { /* Do something */ }

//Simple FAB
FloatingActionButton(onClick = onClick) {
    Icon(Icons.Filled.Add,"")
}

//FAB custom color
FloatingActionButton(
    onClick = onClick,
    backgroundColor = Color.Blue,
    contentColor = Color.White
){
    Icon(Icons.Filled.Add,"")
}

//Square FAB
FloatingActionButton(
    onClick = onClick,
    shape = RectangleShape
){
    Icon(Icons.Filled.Add,"")
}

//EXTENDED FAB
ExtendedFloatingActionButton(
    text = {  Text(text = "EXTENDED FAB") },
    onClick = onClick,
    icon ={ Icon(Icons.Filled.Add,"")}
)

//EXTENDED FAB WITHOUT ICON
ExtendedFloatingActionButton(
    text = {
        Text(text = "EXTENDED FAB")
    },
    onClick = onClick
)

Example:

Scaffold(topBar = { } ,
    //floatingActionButtonPosition = FabPosition.End,
    floatingActionButton = {
        FloatingActionButton(
            onClick = {}
        ) {
            Icon(Icons.Filled.Add,"")
        }
    }
    , content = {
        //....
    })

Use Scaffold

Scaffold provides slots for the most common top-level Material components, such as TopAppBar, BottomAppBar, FloatingActionButton, and Drawer. By using Scaffold, it's easy to make sure these components are properly positioned and work together correctly.

Syntax

@Composable
fun HomeContent() {
    Scaffold(
        topBar = {/**/ },
        drawerContent = {/**/ },
        bottomBar = {/**/ },
        floatingActionButton = {/**/ },
        snackbarHost = {/**/ },
        content = {/**/ }
    )
}

Example

@Composable
fun HomeContent() {
    Scaffold(
        topBar = {
            TopAppBar(title = { Text("Title") })
        },
        floatingActionButton = {
            FloatingActionButton(
                onClick = { /*TODO*/ },
                backgroundColor = Color.Red,
                content = {
                    Icon(
                        painter = painterResource(id = R.drawable.ic_add),
                        contentDescription = null,
                        tint = Color.White
                    )
                }
            )
        },
        content = {
            Surface(modifier = Modifier.padding(24.dp)) {
                Text(
                    text = "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.",
                    fontSize = 16.sp,
                )
            }
        }
    )
}

Output

You can create FloatingActionButton try below @Compose function use your drawable icon.

@Composable
fun MyFloatingActionButton() {
      val icon = +imageResource(R.drawable.ic_add_icon)
            FloatingActionButton(icon = icon, color = Color.Red, elevation = 8.dp)
}

If you want to create a FAB from inside your composable you can reuse this composable function:

@Composable
fun FabAnywhere(
    fabPosition: FabPosition,
    onClick: () -> Unit,
    modifier: Modifier = Modifier,
    content: @Composable () -> Unit
) {
    Scaffold(
        floatingActionButtonPosition = fabPosition,
        floatingActionButton = {
            FloatingActionButton(
                onClick = onClick,
                modifier = modifier,
                content = content
            )
        }
    ) {}
}

Use it like this:

    FabAnywhere(FabPosition.End, onClick = { }) {
        Icon(Icons.Filled.Add, contentDescription = "Add")
    }