This is real iron powder, so will react as iron to the atmosphere ie it will rust.
Stamp or paint acrylic wax or appropriate glue onto your chosen surface and sprinkle with powder. Before the glue has dried, spritz with water or vinegar to activate.
Alternatively, make into an iron paint by mixing with an acrylic medium or Acrylic Wax to make into an iron-based paint. Spritz as before before the paint has dried. Only make as much paint as you need for that project or the iron powder will settle & solidify in the container.
Stain fabric with rust effects by sprinking the powder onto cloth (perhaps through a stencil) - spritz as before. The resulting rusty powder will not be attached to the fabric but should leave a stain behind when brushed off.