diff --git a/ssh-key/src/public.rs b/ssh-key/src/public.rs
index 44c47ae42..9481e8241 100644
--- a/ssh-key/src/public.rs
+++ b/ssh-key/src/public.rs
@@ -249,8 +249,8 @@ impl Encode for KeyData {
             #[cfg(feature = "ecdsa")]
             Self::Ecdsa(key) => key.encoded_len()?,
             Self::Ed25519(key) => key.encoded_len()?,
-            #[allow(unreachable_patterns)]
-            _ => return Err(Error::Algorithm),
+            #[cfg(feature = "alloc")]
+            Self::Rsa(key) => key.encoded_len()?,
         };
 
         Ok(alg_len + key_len)
@@ -264,8 +264,8 @@ impl Encode for KeyData {
             #[cfg(feature = "ecdsa")]
             Self::Ecdsa(key) => key.encode(encoder),
             Self::Ed25519(key) => key.encode(encoder),
-            #[allow(unreachable_patterns)]
-            _ => Err(Error::Algorithm),
+            #[cfg(feature = "alloc")]
+            Self::Rsa(key) => key.encode(encoder),
         }
     }
 }
diff --git a/ssh-key/src/public/rsa.rs b/ssh-key/src/public/rsa.rs
index 5855bff4a..d825fe122 100644
--- a/ssh-key/src/public/rsa.rs
+++ b/ssh-key/src/public/rsa.rs
@@ -1,7 +1,7 @@
 //! Rivest–Shamir–Adleman (RSA) public keys.
 
 use crate::{
-    base64::{self, Decode},
+    base64::{self, Decode, Encode},
     MPInt, Result,
 };
 
@@ -25,3 +25,14 @@ impl Decode for RsaPublicKey {
         Ok(Self { e, n })
     }
 }
+
+impl Encode for RsaPublicKey {
+    fn encoded_len(&self) -> Result<usize> {
+        Ok(self.e.encoded_len()? + self.n.encoded_len()?)
+    }
+
+    fn encode(&self, encoder: &mut base64::Encoder<'_>) -> Result<()> {
+        self.e.encode(encoder)?;
+        self.n.encode(encoder)
+    }
+}
diff --git a/ssh-key/tests/public_key.rs b/ssh-key/tests/public_key.rs
index fcebbdf2c..12263db45 100644
--- a/ssh-key/tests/public_key.rs
+++ b/ssh-key/tests/public_key.rs
@@ -247,3 +247,17 @@ fn encode_ed25519_openssh() {
     let ossh_key = PublicKey::from_openssh(OSSH_ED25519_EXAMPLE).unwrap();
     assert_eq!(OSSH_ED25519_EXAMPLE.trim_end(), &ossh_key.to_string());
 }
+
+#[cfg(feature = "alloc")]
+#[test]
+fn encode_rsa_3072_openssh() {
+    let ossh_key = PublicKey::from_openssh(OSSH_RSA_3072_EXAMPLE).unwrap();
+    assert_eq!(OSSH_RSA_3072_EXAMPLE.trim_end(), &ossh_key.to_string());
+}
+
+#[cfg(feature = "alloc")]
+#[test]
+fn encode_rsa_4096_openssh() {
+    let ossh_key = PublicKey::from_openssh(OSSH_RSA_4096_EXAMPLE).unwrap();
+    assert_eq!(OSSH_RSA_4096_EXAMPLE.trim_end(), &ossh_key.to_string());
+}